The sound has gone from my Toad Alarm, the lights flash and that's it. Any suggestions? Have changed the battery in my key fob.

 

If it's an Ai606 it may have happened because you have pressed another button by mistake. I can't quite remember, it may be button 3 before 1 to arm silently. My toad does this. Try maybe opening drivers door and arm then disarm, or arm then disarm twice? Good luck