Any way to restore your iTunes library?

I somehow put 350 songs to one album, all live music, many duplicates and they were downloaded from a site where I had to download them one by one and name them. I can't just go back and download an album, they are done song by song from live shows. I tried a system restore and that didn't fix the issue. I'm on a PC.

Any help would be greatly appreciated. Looked online and didn't find a solution.