So I bought a used 94 grand cherokee and the factory stereo would spastically work... So I replaced the stereo and now I have no sound coming from the speakers. We have checked to make sure that it is hooked up right several times... What could this be? Please help me I'm going crazy without a radio

Does your jeep have the infinity system?

All jeeps products (late 80s-2001 even the infinity sound systems) are infamous of having really cheap small speaker wire running from the factory radios to the speakers. Then over time from doors opening and closing over and over the wires wear down and begin shorting out. i know in the XJ similar to that year the speakers in the rear hatch are really bad for shorting out. sometimes they work sometimes they dont. I'm currently having the same problem with my front speakers in my 01 XJ. The best thing to do is just run new speaker wire. Its a pain but in the end you will have much better sound qaulity and not have to worry about wether they are going to play. If you are like me, I love my music and it pisses me off when speakers dont work.

I am in the process of running new wire to the dash (for my tweeters) and the front doors. The Doors are super easy... The rubber plug is quite large.

Done this on my jeep and replaced my front door speakers...
Everything is working good now!

I am also deadening the door somewhat too. I will have this in the my build log.

Chances are you have the Infinity system. You need to use the blue and white wire on your pigtail (preamp out) from the head unit. Splice it with the amp / power antenna factory wire. Basically if you do not do this your infinity amp will not turn on and you will get no sound from the speakers. I just went through this last week.