Powershell - if and testpath with not Logic

My Code is this:

If (Test-Path c:\temp\mysunnyday) { New-Item c:\temp\mysunnyday -ItemType directory } Set-Location c:\temp\mypodcast

I wish to say "if not" true. How can i do that? I read this Article http://ift.tt/1xTEtYu

and i tried with -ne ! -not

But nothing works. Can someone help me?