param(
    [Parameter(Mandatory=$true)][string]$Username,
    [Parameter(Mandatory=$true)][string]$Password
)

Import-Module WebAdministration
$appPools = Get-ChildItem IIS:AppPools | where { $_.processModel.userName -eq $Username }

if ($appPools.Count -eq 0)
{
    Write-Host "No AppPools found with username:" $Username -ForegroundColor Red
}
else
{
    Write-Host "Found" $appPools.Count "AppPools to update..." -ForegroundColor DarkGreen

    foreach ($pool in $appPools)
    {
        $pool.processModel.userName = $Username
        $pool.processModel.password = $Password
        $pool.processModel.identityType = 3
        $pool | Set-Item
    }

    Write-Host "Restarting IIS..." -ForegroundColor DarkGreen
    iisreset
    Write-Host "AppPool passwords updated successfully" -ForegroundColor DarkGreen
}