Need Pump Advice, Please

[PopcornGirl]

Hey, I just realized we can play with the font on this board!

Sorry, back to my questions...

Ok, I have a 12,000 gallon, in-ground, gunite pool that is almost 6 years old.
My pool pump is (was?) a Pac Fab Challenger 1 HP -- also about 6 years old.
Tonight, suddenly, my pump stopped pulling water.
Obviously, this seems like a blockage of some sort as it happened rather suddenly and I am going to get that ruled out.
We tried inserting a hose (wrapped with a towel) into the pipe from the pump end (reverse flow direction) and turned it on full-blast to see if that would dislodge anything. A few leaves came out of the skimmer, but that's all. water flow from the hose, out of the skimmer was pretty decent considering our water pressure here is not wonderful.
However, even though some water came through BOTH the skimmer and the main drains, when we tried to restart the pump, NO water came through!
Not even a trickle!
I tried switching fully to skimmer, fully to main drain, and various levels in between. All to no avail.
My pump "sounds" the same -- there is no difference in noise -- but it is not pulling anything!
YES, I cleared the pump basket of debris & YES, my filter cartridges are clean. We took them out last weekend and soaked them and sprayed them till they were almost white again, so it can't be my filter, can it???

My questions are these:
1) What do YOU think is going on?
2) Any suggestions??
3) If I do need a new pump, how much (ballpark) should I expect to pay for pump and installation?
I still consider myself a bit of a novice at all this pool stuff and I do not want to get ripped off. Money is tight and I need to go into this as well-informed as I can!
Thanks so much in advance for any help you can give!