Запуск служб

$strService = "bits"
Start-Service -Name $strService

несколько служб -

$aryServices = "bits", "wuauserv", "CcmExec"
foreach ($strService in $aryServices)
{
 Write-Host "Starting $strService ..."
 Start-Service -Name $strService
}

аккуратный запуск служб -

$strService = "bits"

Get-Service -name $strService |
foreach-object { if ($_.status -ne "running")
{
 Write-Host "starting $strService ..."
 Start-Service -Name $strService
} 
 ELSE
{
 Write-Host "$strService is already started"
}
}