You say you lost all your channels.. do you mean that all the channel memory slots (where you once had entries) are zero-ed out?
If you mean that you do have entries but cannot hear anything, not even NOAA WX on the WX channel.. then something is wrong with the radio.. This happened to me.. Could not get even squelch noise (squelch fully ccw on conventional non-PLed frequency). I had RS fix it under warranty.. it was the potentiometer ("faulty", they say.. maybe wire got detached?).
