My first guess would be that antenna got disconnected somehow. Are both, receiver and transmitter antennas in place? you havent cut them in any way, have you? If not then I would say some component in the radio circuit went bad; reasons may include water in the wrong place, stress or high electro magnetic pulse. Those radios are pretty cheap and a lot of silly things can go wrong with them. I don't know what else i could add.. maybe others on here could suggest something.. if the antenna is fine then you might have to get new radio gear[:'(]

if you take some pics of the rx/tx circuit we could try to detect something unusual but most of the time you dont have blown up resistors or leaking capacitors..etc.