This script will install any available windows updates. If a reboot is required it will setup a temporary user account and enable autologon, then reboot and rerun itself until there are no updates left. Modified gist from https://gist.github.com/joefitzgerald/8203265.

Install-WindowsUpdatesAndReboot.ps1

param(
    $global:RestartRequired=0,
    $global:MoreUpdates=0,
    $global:MaxCycles=10
)

Function Get-StringHash { 
    param(
        [String] $String,
        $HashName = "MD5"
    )

    $bytes = [System.Text.Encoding]::UTF8.GetBytes($String)
    $algorithm = [System.Security.Cryptography.HashAlgorithm]::Create($HashName)
    $StringBuilder = New-Object System.Text.StringBuilder 
  
    $algorithm.ComputeHash($bytes) | 
    ForEach-Object { 
        $null = $StringBuilder.Append($_.ToString("x2")) 
    } 
  
    $StringBuilder.ToString() 
}

function Check-ContinueRestartOrEnd() {
    $RegistryKey = "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Run"
    $RegistryEntry = "InstallWindowsUpdates"
    $AutoLogonRegistryKey = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon"
    switch ($global:RestartRequired) {
        0 {			
            $prop = (Get-ItemProperty $RegistryKey).$RegistryEntry
            if ($prop) {
                Write-Host "Restart Registry Entry Exists - Removing It"
                Remove-ItemProperty -Path $RegistryKey -Name $RegistryEntry -ErrorAction SilentlyContinue
            }
            
            Write-Host "No Restart Required"
            Check-WindowsUpdates
            
            if (($global:MoreUpdates -eq 1) -and ($script:Cycles -le $global:MaxCycles)) {
                Install-WindowsUpdates
            } elseif ($script:Cycles -gt $global:MaxCycles) {
                Write-Host "Exceeded Cycle Count - Stopping"
                Write-Host "Removing AutoLogon and Script User"
                $DefaultUsername = Get-ItemProperty $AutoLogonRegistryKey | Select -Expand DefaultUsername
                Remove-ItemProperty $AutoLogonRegistryKey "AutoAdminLogon" -ErrorAction SilentlyContinue
                Remove-ItemProperty $AutoLogonRegistryKey "DefaultUsername" -ErrorAction SilentlyContinue
                Remove-ItemProperty $AutoLogonRegistryKey "DefaultPassword" -ErrorAction SilentlyContinue
                Remove-LocalUser -Name $DefaultUsername -ErrorAction SilentlyContinue
                Restart-Computer
			} else {
                Write-Host "Done Installing Windows Updates"
                Write-Host "Removing AutoLogon and Script User"
                $DefaultUsername = Get-ItemProperty $AutoLogonRegistryKey | Select -Expand DefaultUsername
                Remove-ItemProperty $AutoLogonRegistryKey "AutoAdminLogon" -ErrorAction SilentlyContinue
                Remove-ItemProperty $AutoLogonRegistryKey "DefaultUsername" -ErrorAction SilentlyContinue
                Remove-ItemProperty $AutoLogonRegistryKey "DefaultPassword" -ErrorAction SilentlyContinue
                Remove-LocalUser -Name $DefaultUsername -ErrorAction SilentlyContinue
                Restart-Computer
            }
        }
        1 {
            $prop = (Get-ItemProperty $RegistryKey).$RegistryEntry
            if (-not $prop) {
                Write-Host "Restart Registry Entry Does Not Exist - Creating It"
                Set-ItemProperty -Path $RegistryKey -Name $RegistryEntry -Value "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -File $($script:ScriptPath)"
            } else {
                Write-Host "Restart Registry Entry Exists Already"
            }
            
            If (!(Get-ItemProperty $AutoLogonRegistryKey | Select -Expand DefaultUsername -ErrorAction SilentlyContinue)) {
                Write-Host "Creating Script User and Enabling AutoLogon"
                $rand = -join ((65..90) + (97..122) | Get-Random -Count 15 | % {[char]$_})
                $DefaultUsername = ("winUpUser" + $rand)
                $DefaultPassword = Get-StringHash -String $rand -HashName SHA256

                New-LocalUser -Name $DefaultUsername -Description "Account for AutoLogon for Windows Updates" -Password $DefaultPassword
                Add-LocalGroupMember -Group "Administrators" -Member $DefaultUsername

                Set-ItemProperty $AutoLogonRegistryKey "AutoAdminLogon" -Value "1" -type String -Force
                Set-ItemProperty $AutoLogonRegistryKey "DefaultUsername" -Value "$DefaultUsername" -type String -Force 
                Set-ItemProperty $AutoLogonRegistryKey "DefaultPassword" -Value "$DefaultPassword" -type String -Force
            }

            Write-Host "Restart Required - Restarting..."
            Restart-Computer
        }
        default { 
            Write-Host "Unsure If A Restart Is Required" 
            break
        }
    }
}

function Install-WindowsUpdates() {
    $script:Cycles++
    Write-Host 'Evaluating Available Updates:'
    $UpdatesToDownload = New-Object -ComObject 'Microsoft.Update.UpdateColl'
    foreach ($Update in $SearchResult.Updates) {
        if (($Update -ne $null) -and (!$Update.IsDownloaded)) {
            [bool]$addThisUpdate = $false
            if ($Update.InstallationBehavior.CanRequestUserInput) {
                Write-Host "> Skipping: $($Update.Title) because it requires user input"
            } else {
                if (!($Update.EulaAccepted)) {
                    Write-Host "> Note: $($Update.Title) has a license agreement that must be accepted. Accepting the license."
                    $Update.AcceptEula()
                    [bool]$addThisUpdate = $true
                } else {
                    [bool]$addThisUpdate = $true
                }
            }
        
            if ([bool]$addThisUpdate) {
                Write-Host "Adding: $($Update.Title)"
                $UpdatesToDownload.Add($Update) |Out-Null
            }
		}
    }
    
    if ($UpdatesToDownload.Count -eq 0) {
        Write-Host "No Updates To Download..."
    } else {
        Write-Host 'Downloading Updates...'
        $Downloader = $UpdateSession.CreateUpdateDownloader()
        $Downloader.Updates = $UpdatesToDownload
        $Downloader.Download()
    }
	
    $UpdatesToInstall = New-Object -ComObject 'Microsoft.Update.UpdateColl'
    [bool]$rebootMayBeRequired = $false
    Write-Host 'The following updates are downloaded and ready to be installed:'
    foreach ($Update in $SearchResult.Updates) {
        if (($Update.IsDownloaded)) {
            Write-Host "> $($Update.Title)"
            $UpdatesToInstall.Add($Update) |Out-Null
              
            if ($Update.InstallationBehavior.RebootBehavior -gt 0){
                [bool]$rebootMayBeRequired = $true
            }
        }
    }
    
    if ($UpdatesToInstall.Count -eq 0) {
        Write-Host 'No updates available to install...'
        $global:MoreUpdates=0
        $global:RestartRequired=0
        break
    }

    if ($rebootMayBeRequired) {
        Write-Host 'These updates may require a reboot'
        $global:RestartRequired=1
    }
	
    Write-Host 'Installing updates...'
  
    $Installer = $script:UpdateSession.CreateUpdateInstaller()
    $Installer.Updates = $UpdatesToInstall
    $InstallationResult = $Installer.Install()
  
    Write-Host "Installation Result: $($InstallationResult.ResultCode)"
    Write-Host "Reboot Required: $($InstallationResult.RebootRequired)"
    Write-Host 'Listing of updates installed and individual installation results:'
    if ($InstallationResult.RebootRequired) {
        $global:RestartRequired=1
    } else {
        $global:RestartRequired=0
    }
    
    for($i=0; $i -lt $UpdatesToInstall.Count; $i++) {
        New-Object -TypeName PSObject -Property @{
            Title = $UpdatesToInstall.Item($i).Title
            Result = $InstallationResult.GetUpdateResult($i).ResultCode
        }
    }
	
    Check-ContinueRestartOrEnd
}

function Check-WindowsUpdates() {
    Write-Host "Checking For Windows Updates"
    $Username = $env:USERDOMAIN + "\" + $env:USERNAME
 
    New-EventLog -Source $ScriptName -LogName 'Windows Powershell' -ErrorAction SilentlyContinue
 
    $Message = "Script: " + $ScriptPath + "`nScript User: " + $Username + "`nStarted: " + (Get-Date).toString()

    Write-EventLog -LogName 'Windows Powershell' -Source $ScriptName -EventID "104" -EntryType "Information" -Message $Message
    Write-Host $Message

    $script:UpdateSearcher = $script:UpdateSession.CreateUpdateSearcher()
    $script:SearchResult = $script:UpdateSearcher.Search("IsInstalled=0 and Type='Software' and IsHidden=0")      
    if ($SearchResult.Updates.Count -ne 0) {
        $script:SearchResult.Updates |Select-Object -Property Title, Description, SupportUrl, UninstallationNotes, RebootRequired, EulaAccepted |Format-List
        $global:MoreUpdates=1
    } else {
        Write-Host 'There are no applicable updates'
        $global:RestartRequired=0
        $global:MoreUpdates=0
    }
}

$script:ScriptName = $MyInvocation.MyCommand.ToString()
$script:ScriptPath = $MyInvocation.MyCommand.Path
$script:UpdateSession = New-Object -ComObject 'Microsoft.Update.Session'
$script:UpdateSession.ClientApplicationID = 'Packer Windows Update Installer'
$script:UpdateSearcher = $script:UpdateSession.CreateUpdateSearcher()
$script:SearchResult = New-Object -ComObject 'Microsoft.Update.UpdateColl'
$script:Cycles = 0

If (!($script:ScriptPath -eq 'C:\ProgramData\winUpdate.ps1')) {
    Copy-Item -Destination 'C:\ProgramData\winUpdate.ps1' -LiteralPath $script:ScriptPath
    $script:ScriptPath = 'C:\ProgramData\winUpdate.ps1'
}

Check-WindowsUpdates
if ($global:MoreUpdates -eq 1) {
    Install-WindowsUpdates
} else {
    Check-ContinueRestartOrEnd
}

I just used this... It locked me out of my computer, activated the admin account along with a password for it, obviously I won't know what that is.. that would be okay but for the fact that MY USER is not availabe on the logon screen and none of the fixes I've tried have helped..

Like, it's probably me being dumb but I've tried enough fixes to have realised by now,, Is there anything in your script that would cause that and you know how to undo it?

Don't take this as me sayingn you are malicious in any way it's proall a bug of some sort but damn it's a bad bug...

Also I changed the admin account password in safe mod and it didn't work, when I leave it blank it still says wrong password, when I typ in "123" which is what I set, it says "your account has been disabled".

Edit: @d4rkeagle65

Yeah that fucked my system up in a way I;'ve nevber seen... currently reinstalling Windows on the laptop I used it on so not the worst thing.. but using it on my main would have been disastrous if it did the same thing.

@d4rkeagle65 Actually, I'm using Win11 Enterprise IoT so maybe there was some weird user interaction there ... ?