A question for the car experts out there

How long can a car sit/ not be used before things start to go wrong with it? I have a 97 Toyota car and it's been parked in a garage for about 2 months now how long can it sit there before things start to get screwed up in the motor from it not being used any? I'm gonna be in another state for a year and i can't use it! The garage door is always open but it can't rain or snow on my car.