MK2 Golf GTD wont start

[Wannabechanic]

Hi im new to forums, and I'm stumped. Ive read a lot on here and VW Vortex looking for answers but i cant find anything.
I have an old manual 1991 Mk2 Golf Gtd 4 door hatch, sitting in my garage. I want it out of the garage obviously, so i can use the diesel to drive my long distances and drive my bmw for other daily needs.

The Golf wont start anymore, I bought it and it was starting and it just needed a timing belt replacement, and new glow plugs. I did that and then it wouldn't start without a jump. Now it won't start period.
I got a new starter cuz it seemed to be the problem but no change. When I turn the key i hear the starter shoot out and spin then nothing else. It doesn't seem to grabbing the flywheel.

What should I check for? If anybody has any ideas or help for this rookie, itd be much appreciated, this car's help info has proved to be limited..
Thank you

[libbydiesel]

Put the trans in neutral.  Put a socket on the big bolt (19mm) in the center of the crank sprocket.  You'll want at least a 1/2" drive ratchet or breaker bar.  See if you can rotate the crank clockwise.  If not, then your issue is that the engine is seized.  If so, then you confirmed that the engine is not seized.  If your starter spins but the engine does not crank, then there are very few possible issues.  I'd start with pulling the starter back out and checking the ring gear it should mesh with.

[Wannabechanic]

Ive tried turning the flywheel at the point where the starter goes in, and it rotates, is that the same? Ill try it your way too. And ill look at the two gears again, I dont think any teeth had been ground down. Thanks though ill check these things out.

[libbydiesel]

It's not exactly the same although if it seemed fine that way, then it probably is.  The flywheel could potentially spin without the crank rotating if it has come detached from the pressure plate but it is highly unlikely that it would seem ok.  Similarly, it could spin without the crank spinning if the pressure plate has come detached from the crank but again it would probably be obvious. 

[Wannabechanic]

okay, that's understandable, Ill check it next chance I get, thank you very much.