engine tempt. gauge not working

Not sure how to do it yourself but I don't think it would be expensive to have a mechanic fix it. When my gauge broke on my 00' Jetta, I managed to crack a water hose while driving it and didn't notice it (it was 0 degrees temp outside and there was a lot of steam coming from all running exhaust pipes that night). I drove it too long without noticing the over heat and ended up blowing a head gasket. I'm sure something like that is your fear. When the mechanic repaired it, the temp gauge worked. The mechanics weren't even aware of it because I forgot to mention it. That said, I believe that the gauge repair shouldn't be too bad. It's probably electrical which wouldn't be surprise with a Jetta.