Depends on your state and it will be a bit of a hassle. The first thing is talk to your local tag & title office. Explain the situation and then see if you want to proceed.
In short (Tennessee) you'll have to have the property owner file a lien against it, and then probably apply for a new title if the owner doesn't respond in X amount of days.
If the owner doesn't respond you'll be required to run a few ads in local papers advertising the car in the want ads under the legal section asking anyone who has ownership or claim to come forward..
After that time period has passed they should issue you a title...
Shouldn't be a difficult process, but these things always seem to be a little more difficult than forecast.
However it has been a long time sitting it should be easier than a car that was parked just a year or so ago.
Good luck! I'd for sure contact the local tag and title office and have them run the VIN for the last year it was registered.
Should be a snap!