I bought a '70 Barracuda recently. The guy I bought it from said it had been sitting a few months and suddenly the driver's side door won't open. So I brought it home and compared the movement of the mechanisms in the working door to the non working door and they both seem to be moving the same parts. Both the inside and outside door handles move the inner parts freely, but it just doesn't seem to be breaking the door free. Neither of the doors have locks. The locks have been completely taken out before I even bought the car. I'm not familiar with these moving door parts but is there a chance it is still locked even without the keyhole lock in place? If so how can I free it up? Thank you all for your help.

is there any play back and fourth or is it stuck solid.

Yes, absolutely it can be locked. The lock cylinder just moves a pushrod which actuates a lever on the latch. You'll just have to get in there with your fingers, find it, and try to move it.

It would help if you were familiar with it, but you can probably just tinker with it. Could be broken, too, but try this first