Blower Motor Changed Direction

This could be a capacitor start motor. If the capacitor failed it would not start. That is why it was humming. When you turned it by hand you likely turned it in the wrong direction and it will run in the direction you first turn it.

Replace the starting capacitor.

Or the starting switch, same issue, different cause.

if it is a 3 phase motor, you have lost a phase. Similar issue, different solution.

If it is a single phase motor:

besides capacitor if there is a rotoray clutch that needs to be checked, one of the windings (starting) can be dammaged.

If it is a three phase motor:

check the supply phases to be R,Y,B in sequence as well as the condition of bearings

All my Doe, you stated here that you changed the blower motor, http://cr4.globalspec.com/thread/58612/Blower-Motor-in-AC-Won-t-Restart, I think you may have wired it wrong.

Do yourself a favor and hire a professional. This should all be a fairly inexpensive fix. Someone that knows what they are doing can have this fixed in about an hour.

You have already committed too much time, (and too many posts), to this problem.