An Unknown Error Occurred

I deleted subfolders and files in the library folder awhile ago hoping to clear up storage and not knowing any better. When I restarted my computer all my accounts and settings for programs were deleted but it was all fine I just put everything the way it was before. However, it also logged me out of my Apple account but whenever I sign into system preferences or into the app store with my Apple ID it tells me that the verification failed and an unknown error occurred. I'm not sure if I deleted a file that's affecting me signing in. Is it possible for me to restore the deleted files? How do I fix this?