I have found this code on internet which is perfect the only problem is how to use get-childitem in this code so that it copies the most recent zip file and unzips it. here is the code.
$path = "C:\Deployments"$destination = "C:\_Temp"
$shell_app= New-Object -com shell.application
$files = Get-ChildItem -Path $path -filter *.zip -recurse
foreach($file in $files) {
$zip_file = $shell_app.namespace($file.FullName)
$copyHere = $shell_app.namespace($destination)
$copyHere.Copyhere($zip_file.items())
}