[SOLVED] CDJ 400 won't load tracks!

Hello, I have a problem with one of my cdj 400s. It was all working perfectly fine but now when i press down on the scroller it won't let me load a track. It will let my scroll through the tracks but won't let me load it. If anyone knows what part I would need to replace or how to do a quick fix or any places that repair cdjs in bristol that would help a lot. I need it fixed ASAP! Cheers.