Your dream car is parked in out of the elements, but it's not secure because the garage door won't lock. Most garage doors have two horizontal bars that move out from the center of the door into slots along the side of the door in the door track, effectively locking the door in place. Over time, these bars can shift slightly out of position so that they are no longer correctly aligned with the locking slots. To realign the bars, unscrew the guide brackets on the edges of the door so that they are loose enough to move, and then reposition them so that they smoothly guide the locking bars into the locking slots. Lubricate the lock mechanism with machine oil and you're done.
The power to your garage is out with the door shut, and you need to get your car out or you'll have to take a bus. You'll notice a cord—usually with a red handle—dangling down from the guide track that the opener uses to open and close the door. This is the manual override. Once pulled, it allows you to open and close the door with your own power in the form a little elbow grease.