Function to reset a user's password

d7_password_reset.php

<?php

function password_reset(){
    global $user;
    $hashthepass = 'password'; /* Your password value*/
    
    require_once DRUPAL_ROOT . '/' . variable_get('password_inc', 'includes/password.inc');
    $hashthepass = user_hash_password(trim($hashthepass));
    
    if (!$hashthepass) {
      
        return FALSE;
    } else {
      
        db_update('users')
        ->fields(array(
          'pass' => $hashthepass
        ))
        ->condition('uid', $user->uid)       
        ->execute();
    }
 }