Did you actually go to your son's library & delete things, or did you just go thru LW's tools > options & stop sharing some folders? Unless you deleted the files then they should still be there...just not shared & maybe not showing up in his library.

Use your computer's search to look for some of the file names...see whether they're still around

If you open LW & then go tools > options > saving, you'll see the path to the folder with your saved files. Do the same in your son's LW & you'll see the path to his saved folder. You can find those folders on your computer & then copy & paste from one to the other. Or, if the files haven't actually been deleted, you can add files back into your son's LW library by adding the folder(s) for sharing. Again, this can be done from LW's tools > options.

If you tell us which version of LW you're using, we can probably help you a bit more