doberzus

I was driving today and I looked at my speedo gauge and what do you know?....I was going 90MPH!!!! But luckily my digital speedo was on and it showed 25MPH (it was in a 35MPH zone) haha so I look over again and the needle is stuck at 80, only when i turn off my car does it go back down to 0..... now im thinking how much is this going to cost to repair??!! What is the cause of this can anyone help me?..... thanks in advance guys