96 s-10 blazer speedometer-odometer

just changed my heater core and i pulled the instrument cluster out. put everything back but now my speedometer and odometer doesn't work. everyother gauge works fine. i'm just wondering if the computer or something need reset? it has 108,000 miles nothing else wrong. can't find any manuals on this subject any help would be appreciated.

I would take out the dash panel again and MAKE sure that ALL the plugs are seated in their sockets. It seems like maybe one of the cables are not seated properly. Hope this solves the problem.