97 has problems shifting

My mom has a 97 escort. Last week she started driving it and told me there was something wrong with it. I got in and drove it and noticed that it doesn't shift out of 1st gear and the speedometer doesn't move. The car sat in the driveway for a couple of days and while taking it to a mechanic, everything worked fine. Nothing was found wrong with it and the car returned home. The problems returned and so we took it to another mechanic. The mechanic changed a sensor (I'm assuming the sensor to the transmission that tells when to shift) and checked the wiring and it still does the same thing. What should I check next?

you should take it back to the mechanic that tried to fix it, he now needs to work on it for free, since you paid for something to get fixed and it didn't.