Well I got this car hoping it wouldn't be this serious but I tried to turn the engine by hand and it won't budge at all.

Not in gear. Tried rolling backwards in 4th. Removed plugs tried again. Won't budge.

What do you guys think it is?

 

Could be carbon lock, could be oil starved rotor bearings... Could be a broken off and wedged apex seal.. How long was the car sitting before you got it? What did the previous owner tell you about its running condition?