I need help again with my 1995 ford probe gt alarm system?

It rained for like 3days where i live and i know that i have an alarm for my car but during the night when the wind was blowing real hard my car alarm went off and i had the car for 2years and this never happened before?????? but when i purchased the probe i never had the alarm piece for it i only had the key so the alarm started going off and i know from having other ford vehicles you have to put the key in and turn it to cut the alarm off and also the anti-theft light blinks in the car now and it never did that before????? is it possible that the alarm can reset itself????? also can i go to a dealership and get a new alarm piece?????? and what would it cost???? im clueless someone help me out please