help find a new fob?

I left my car (fob) out in the rain one night as it drop of the bunch of keys i was carrying,it must have got trot on dozens of times,i blow dry with hair dryer,plus change the battery,to my dismay it still will not work,every time i open the door the alarm goes mad,if i removed the fuse,nothing works,Help
Its a Rover Metro s 1999,i do miss driving my (tincan)pet name,