List Folders which are not updated in last X days

I have windows base File sharing server (with above 100 shared folders for users) for users where users copy there files on daily basis for backup purposes. Some users forget to do this, and after many days or in disaster recovery, it apper that user was not maintaining his backup folder. This creates problem for IT Dept. At a moment we check every user by daily browse throught there folders and sort by last modified.I want to this with some scripting.

Folders Structure is as following

D:Backup

D:BackupUser1Folder1 [contains main backup files of user] D:BackupUser1Folder2 [contains junk data only for user]

D:BackupUser2Folder1 D:BackupUser2Folder2

and so on

Now I want to list folder names which are not updated(modified) in last X days. ) but only FOLDER1 should be scaed which contains the actual backup files)