Passat 93 not starting after sitting for long time.

Hi,
The battery of my 93 passat was dead, so I let the car sit for a few months (~5). Now I have replaced the battery. I tried to start the car, but it won't! There;s lights and sounds when I put the key in, and a couple of times the RPM indicator jumped a tiny bit when I turned the key. But still it won't start. Now there is not evey that RPM jump, just a tiny sound.

A mechanic says that it might be the starter motor that it might have gotten stuck, and hitting it might help. But where is it? What does it look like? Could it be something worse? Also the coolant seems to have disappeared but there is not marks that it ever leaked out of the car.
Any help would be greatly appreciated!