Use GitHub CLI to enable all workflows that were disabled due to repository inactivity - either for all repos in a given org that you manage, or (by default) your personal repos.

gh-enable-all-inactivity-disabled-workflows.sh

function gh-enable-all-inactivity-disabled-workflows-for-org () {
    org=$1
    gh repo list --no-archived --limit 1000 $org | cut -f 1 | xargs -I REPO sh -c 'gh workflow list --all -R REPO | grep disabled_inactivity | cut -f 3 | xargs -I WORKFLOW sh -xc "gh workflow enable WORKFLOW -R REPO"'
}

function gh-enable-all-inactivity-disabled-workflows () {
    # for user
    gh-enable-all-inactivity-disabled-workflows-for-org

    # for his organizations
    for org in $(gh org list --limit 1000); do
        gh-enable-all-inactivity-disabled-workflows-for-org $org
    done
}