Ok so I have a 2001 Golf1.8t. I had Car Toys install a Sony Xplod cdx-m630 about eight months ago. I also installed 2 12 inch subs. Everything was going perfectly until the head unit started acting weird. First the lcd screen that pops out wouldn't show anything, but everything else worked fine. Then the buttons stopped working, so now I can't control anything on it!! However, it does turn on when the car is on.. I need help!!

This is a cut and dry issue of and internal fault, there are 2 ways you can go about this.

1. Get an electronics expert to pull it apart and have a look for you.
2. replace under warranty, if still valid.

Most internal faults are more expensvie to repair than to replace. Take your car back to the place you bought i from and let them know the problem.