What caused my digital speedometer to stay stuck on zero mph while driving?

What is your question?

It happened after I installed an aftermarket radio and I didn't have enough to buy the harness adapter so I straight wired the radio and the two wires that control the dimmer switch and lights in the dash touched the ground wire and my speedometer went from zero to three then back to zero. Now when I drive it just shows zero mph and its not recording mileage either. Also my light in the dash work when I turn on my headlights but the dimmer switch doesn't dim or brighten the lights in the dash the only thing it does is turn on the light in the top if the car if the switch is pushed all the way up. Please give some advice because I hate driving and don't know how fast I'm going.