How many OBDII sensor codes are there?

A lot of them, so What's the problem here?

Would the be 99 at one time? The issue is we received our vehicle back after repairs with a ton of issues. They took it to the dealer to have it looked at and they noted that there were 99 codes present. Some of the being sensors. They erased the codes and didn't fix any issues. Based on their belief that in a collision damage is isolated to the area hit. Engine lights and leaks are everywhere. Just trying to figure out if I could retrieve information on that date or if it's gone forever and spend everyday with new issues popping up.