Engine will not crank over?

Additional info: 1) Removed starter, bench tested OK. Put back in car.
Turn key you hear it engage but it doesn't turn over the engine. 2) Can't
check compresion because engine will not crank over. 3) Loosened
alternator belt and power stearing belt. Tried to move Crank shaft with
breaker bar but would not move in either direction.

Seems like the engine has siezed up. What is the best way to diagnose the
possibility of a crankshaft repair verses a camshaft/head/valve repair.
Owners manual says not to turn with wrench to avoid valve damage.

Also, would like to remove timing belt cover but can't seem to remove
without removing crank shaft pulley. Is there another way? The timing
belt look OK is it possible is jumped and now we have damage to valves?
Car has 105,000 miles on it. What's the best alternative: Rbuilt engine,
rebuilt head (if that is this issue), used engine or simply rebuild it
myslef?

Additional Info: Removed valve cover and all valve rods seem to be pressing
against each of the rocker arms like they should be. Each rocker arm is
attached to the lash adjuster like it should be. All the springs look OK.
The cam shaft is not broken. Car actually has 114,000 miles on it, more
than I thought. I was going to remove the timing belt and then gently
rotate each cam and the crank shaft individually to determine if the issue
is in the top of the engine or the bottom but the repair manual says:
Caution do not turn the crank shaft or cam shaft/s after the timing belt
has been removed as this will damamage the valves from contact with the
pistons. Do not try to turn the crank shaft with the cam shaft sproket
bolts and do not rotate the crank shaft counter clockwise.

So, how do I locate the root cause of why I can't turn the engine over
using a breaker bar or starter. Keep in mind I have the spark plugs out.