However, it will change gears if you manually move the gear shift to 2nd.

I'm pretty sure the transmission is fine. It has been running great. I took it to a friend to change out the fuel pump and then all of the sudden it wouldn't shift gears. I've looked into it and I have seen that it may be a few things:

1. The shift control Solenoid
2. The Transmission Control Unit
3. The transmission itself went out (which I don't think happened)

How do I figure out where to start?

Other issues: the gear shift is locked unless you put the key in to release it. Not sure if this is related. I switched out the brake switch about a month ago when this happened. Now it is happening again.

Thanks for the help!

 

By chance you did you have the radio on while the fuel pump work was going on? Check the fuses - under hood as well as under dash.