Unless you are lucky it may not be an easy problem to resolve there are probably several possible causes. If the radio still produces sound, it is probably a fault within the radio such as a dry joint or intermittent connector. It may possibly be a problem with the connectors outside the radio in which case un-plugging them and plugging them in again may clean them. The problem is that if you disconnect the radio then you probably will need to enter the radio code before that radio will work again and you also have the problem of getting to the connections in the first place.
If the radio goes off all together it could be an intermittent connection on the fuse but removing and replacing the radio fuse could also result in needing to enter the radio code again.
If a radio plays up when the car is still under warranty it will often be replaced as it is normally the quickest way to solve the problem.
