You have multiple places to look:
1: Speaker wire. I've had micro-rips in my speaker wires from my kitten chewing on them. Inspect them closely to see if that may be your case. If it is, cut the wires, strip them,solder them back together, and insulate them with shrink tube or electrical tape.
2: Disconnect at the speaker. See if you can open your speaker up and inspect the connection on the speakers. Re-solder if necessary.
3: Main Board. Vibrations may have damaged components on the main board. If you can access the board, inspect it for any visual breaks in solder connections. If those all check out, try to see if you can identify any of the ICs. If you can find specs on the ICs you may be able to test them with a multi-meter to see if they match specs. If nothing else, tracing with a voltmeter can tell you where there's a power disconnect.
4: Also an option, if you have a wired speaker remote (like many of the Logitech speakers), there may be damage in the controller. Inspect it in the same manner as the main board.
If you give us the maker and model of your speakers we may be able to help you find more detailed diagnostic information. Good luck!