I've heard reports of such, but disk cleanup has never done such in any of the office, lab or home machines.

What it did expose it that your BACKUP and DISASTER RECOVERY PLAN didn't work. You may not been keeping your backup current to survive drive failure or machine theft.

If you have no backup, then this may be your lesson that hard disks are temporary storage. No OS yet assures us that the files will stick around.

Best of luck,

Bob