I changed the disk brake in the axle, but all the gears slid to one side as I was putting it back together. Now the wheels move in opposite directions. How do I align the gears to work correctly?

If you are turning one side forward and the other wheel goes backward, that is correct with a standard differential.

Yes this is the indication. The problem is it never unlocks. I can't even push the mower in nuetral. or without the belt installed.

Dana 4450-1 manual (http://www.chung-sim.com/dana.4450-1.html)

I did not open and review this manual, but perhaps you can find it useful.

Is it possible your parking brake is not disengaging, when the engine is off? I am assuming when the engine is running you have NO problems, is this a correct assumption?

Can it be pushed in neutral with the engine on? If so check the clutch, and brake linkage, before you tear your trans apart.

Hopefully its an adjustment and not a teardown job. I think the gears are aligned correctly as ma0641 said.

Please let us know how you came out.

Sorry, I thought it was a car transaxle, not a mower.

I understand why you didn't look at the manual. It's a website where you give info and commitment to do/buy certain things before you can download it. I'm out on that. This is a mower transaxle. And it won't go even with the belt removed. I can't push it or do anything. Everything else is very good. As I mentioned, I replaced the disk brake inside as the ears broke off and the was no stopping. I lifted one side and all the gears on the shaft with the disk slid to one side and now the gears aren't lining up as they should. I have a breakdown of the parts but it won't show the gear alignment.

Your linkage pins are inside the gearbox, so requires the whole transaxle assembly to be removed and inspected. It's a big complicated job. Got tools and a worktable? It will have to be removed to be serviced either by you, or the professional you take it to. Take it out, take a look. Go from there.

Maybe it's time to makes some phone calls for some hands on help, at least see what they say.

Hi,
Always instructive if you tell the mower brand, model transaxle brand and model. I can tell you where to find them, but I have to have some clue.
Peace,
Clarke