Why won't my iTrip pick up FM frequencies anymore?

I'm about ready to hurl my $50 iTrip transmitter out of the window. Don't bother asking me which model I have, or which "generation" it is. All I know is that it's the model that allows you to charge your iPod while playing, and it has +/- buttons and a round SmartScan button next to the LED screen. Anyway, I have no idea which combination of buttons I inadvertently pressed, but I can no longer get FM stations with my itrip. What I get when I scroll through are some strange single-digit numbers. In other words, instead of 87.9 or 88.1, I have 4.5 or 0.1, which does me no good. I've tried switching from LX to DX and back, but it does me no good. What do I do to get it playing again? I miss my music!!