Have you checked the battery voltage, and tried jump starting it?
If it's been sitting the battery may not have enough to turn it over.  The
turning by hand does have me a little worried though, pull the plugs and
try turning it by hand..

----------
> From: Doug <dbacky@imperium.net>
> To: Multiple recipients of list <vanagon@lenti.med.umn.edu>
> Subject: Please help my 81 Vanagon live again :(
> Date: Monday, December 09, 1996 9:52 PM
> 
> After dropping the gas tank to have a leak repaired, my faithful
companion
> refuses to start. Turning the key brings on the usual lights, but the
engine
> won't crank over. The battery is fully charged and I've had the starter
> checked and cleaned all the crud off of the contacts, but still no go.
The
> really scary part is that I think the engine is seized up because I can't
> even turn the engine over by hand. How could this happen? The thing ran
like
> a champ before having the tank r&r'ed. It did set for a few weeks, but
I've
> done that before and had no problem getting her/him to run. 
> 
> I guess the bottom line is: What magic spirit do I use to un-seize the
engine?
> 
> thanks
> doug@imperium.net
> 81 Vanagon 
> 80 parts Vanagon (4 sale, sorry no motor or trans)
> 83 Jetta