1999 Nissan Pathfinder car won't heat - fan/blower out?

I don't know a lot about cars and wanted to find out what the problem with our car could be and a ballpark cost to fix before we try to take it in.

Our Pathfinder's heater recently stopped working. All digital controls are working and we can feel that there's heat being generated, but no air is blowing out of the vents.

Can you give me an idea of how to go about getting this fixed? Is there more than one possible cause for this, and will the solutions vary wildly in cost? Any help or advice you can give will be most appreciated!

(if it makes a difference, our car is an LE trimline and is actually a 1999.5)