Function Lock-RemoteWorkstation
{
param(
$Computername,
$Credential
)
    if(!(get-module taskscheduler)){Import-Module TaskScheduler}
    New-task -ComputerName $Computername -credential:$Credential |
    Add-TaskTrigger -In (New-TimeSpan -Seconds 30) |
    Add-TaskAction -Script `
    {
    $signature = @"
    [DllImport("user32.dll", SetLastError = true)]
    public static extern bool LockWorkStation();
"@
    $LockWorkStation = Add-Type -memberDefinition $signature -name "Win32LockWorkStation" -namespace Win32Functions -passthru
    $LockWorkStation::LockWorkStation() | Out-Null
    } | Register-ScheduledTask TestTask -ComputerName $Computername -credential:$Credential
}

Function llm #lock Local machine
{

 $signature = @"
    [DllImport("user32.dll", SetLastError = true)]
    public static extern bool LockWorkStation();
"@
    $LockWorkStation = Add-Type -memberDefinition $signature -name "Win32LockWorkStation" -namespace Win32Functions -passthru

    $LockWorkStation::LockWorkStation()|Out-Null
}