Cruise control not working.
 

When I bought the truck a couple months ago the cruise light would come on but wouldn't set to cruise. Now I can hit the cruise button and I get nothing. Please help me!

The buttons on the steering wheel just modify a signal voltage from the PCM, to suggest to the PCM what you want. So far as I know, the PCM will power the cruise, regardless of any other problems, provided it actually gets the signal from the steering wheel buttons. If you don't already have one, get the service manual for your truck from here. Wiring diagrams are in section 8w. It will show the resistances of what the various buttons are, so you can calculate what return voltage should be. Test that first. See what ya get. If you don't get anything at all..... might be as simply as a bad clock spring in the steering column.

First thing to check the fuse, depending on the year there is a vacuum/servo near the battery the controls the cruise, there is a cable/vaccum line that runs from the accelerator on the throttle body, another thing to check is the button inside on the actual brake pedal linkage. There are a couple of components that control it, that actual pcm circuit as mentioned above, the actual servo, and the vehicle speed sensor (this is an input to the pcm and would need to be looked at in the wiring diagram).