Check Engine Light-95 S10 Blazer

I have a 95 blazer.Recently did some work by muffler I happened to unhook it. I hooked it back up where there was slight gap between the muffler and exhaust pipe. I drove about 30 miles home and on way home my check engine light started to flash (it was on but not flashing) so now I completely unhooked it and left it hanging loose and the light is now completely off. If anyone can help me out I'd appreciate it!