'00 Tranny died suddenly. Culprit???
 

I have a 2000 Taurus SEL. Ran excellent. No prior problems at all. Ran like a new car. Today, all of a sudden as I turned a corner the tranny just lost the gear and never recovered. I coasted onto the curb. Tried all gears... nothing! It's like constant neutral. No rev. no drv... nothing. I assume the linkage is okay because when i put it in park and try to push the car it won't roll. In all other gears I can push it fine. The weird thing is that I never saw it coming. Like I said, that car always shifted like a charm, no hesitations, no bucking... nothing. I let the car cool off for about 3 hours and then tried it again and still nothing. If this is an easy fix, I would like to do it myself since I've worked on all my prior cars. Can someone point me in the right direction? Maybe a checklist of possible faults? Thank you.

UPDATE:
 

Not sure what this means but maybe it can hint towards the cause of the problem. I checked the trans. dipstick dipstick today and saw that about 6 inches of the dipstick was covered in trans. fluid instead of only the very tip (an inch or so) where the 'fill level' crosshatching is. The car was sitting at a parking lot for a whole day so all fluid should have drained down by then. How the heck can the fluid level get so high so suddenly? I've always kept up with my fluids and have never seen anything like that before. My fluid level has always been in the normal. I've never added fluid.

UPDATE#2:
 

UPDATE: I unplugged a transmission line from the cooler at the radiator and started the car.... nothing! There was no fluid pumping. Now, here's the question; what's the best way to tell if it's a blockage somewhere, or if it's a bad pump? (BTW, I confirmed, it is an AX4N).

RE: UPDATE#2:
 

Well, I took apart the valve body and pump assembly. The pump looked like new. everything was intact. However, when I grabbed the pump shaft and tried to spin it by hand, it spun!!! You could feel it slipping past the splines. When I slid out the shaft you could see the teeth worn away. So my question is, will a new shaft fix this or will the torque converter have to be replaced as well. And if so, is a T/C replacement beyond the scope of a home mechanic? Should I just bite the bullet and bring it to the shop?

Friend. The same thing happened with my friend's mondeo. The fluid level was the culprit.Got the leakage fixed and now things running fine