HELP!!! I woke up this morning to find that my headlights were on BUT lastnight they were off?

Last night around 2.am i went to go grab a bite to eat, and it was unusually cold (40 degrees)and my car had frost and dew(water) all around it..i let it heat up a little then went to go get my food. When i got back home i turn my twilight lights off because they have a standby of like 1min after car is off to deter criminals after exiting and went in the house with everything off. This morning the weather was back to normal and was mild(65+degrees) but i saw that my lights were on and now my car wont start. Could the weather have a play in this? or sensors? This is the first time this happend CAR:Cadillac Catera 2000 Base Dayton,Ohio