Finding modified date of a file/folder

If you run the Get-Item or Get-ChildItem commands these will output System.IO.FileInfo and System.IO.DirectoryInfo objects that contain this information e.g.:

Get-Item c:\folder | Format-List  

Or you can access the property directly like so:

Get-Item c:\folder | Foreach {$_.LastWriteTime}

To start to filter folders & files based on last write time you can do this:

Get-ChildItem c:\folder | Where{$_.LastWriteTime -gt (Get-Date).AddDays(-7)}