Local files got deleted after syncing

I have a large collection of music in my PC that I've been recollecting from CD's and tapes, then saving them in my computer for many many years. When I wanted to sync this music with iCloud through iTunes, after the sync was done the local files of the music in my PC got deleted and they didn't even go to the recycle bin. And the synced music in iTunes is incomplete, there are too many files missing. How can I get my deleted music back to my PC's hard drive?