You have one of three problem, the radio, speakers (unlikely) or the speaker connection to the radio.
What you need to do is remove the radio to make sure all connections are plugged in. If they are, I recommend taking the radio to a stereo shop that can check bench test it. Most shops have speakers, a power supply, and can tell you if the radio is bad in under 5 minutes. Also, most don't charge to do it.
In this case, if all connections are attached and tight, I feel the amp in the stereo has gone bad and is no longer supplying a signal to the speakers.
Let me know what you find or if you have other questions.