The AWD stopped working. Only the front wheels drive.

On this website? Where?

At the top of this page where it says ESTIMATOR!

How am I supposed to do that if I don't know what the part(s) are called?

Maybe you should have written it down! I am pretty sure the mechanic said something about a DRIVESHAFT. Another name for it is the PROPELLER shaft. No price from your mechanic?