For month on end, whenever I try to download or update ANYTHING on cydia I get a repository not found error, Saurik error, POSIX eroor, or something else. NONE of the important or big repositories are working guys, any idea whats wrong?
You must have some major files missing on your system. You mightve accidently removed something and all it takes is one file. So what I would do is just remove cydia completely and reinstall. That's your best bet.