2000 Suzuki Grand Vitara Won't Start & stuck in park, c

Please help! My wife's Grand Vitara is stuck in a Target parking lot. It won't start, and it won't come out of park even. The battery is 3 months old, and I already had it check and it is good. There are brand new battery terminals too. Guy at the auto store said that something must have shaken loose at the gear shifter, says that would cause a car not to start, is this something a layman can fix, or am I going to have to call someone to fix it on the spot?

Thank you for any help