Any number of things could be wrong, most transmission related.
If you smelled anything burning when you were driving yesterday, it's possible the transmission fluid's been overheated due to the oil cooler having a restriction and has chemically broken down.
You need to check the transmission dipstick to see if the fluid is still pink/red and not black or brown.
You might want to try giving just a little gas with the engine running and the car in gear to see if the torque converter will eventually lock up (which will kick the car in to gear). And when I say a little gas, I mean just that. You don't want to rev up to 3000 RPM or anything like that.
You might also check to see if the transmission is leaking since you shouldn't have to "top off" transmission fluid. But it'd have to be a major pressure leak to keep the car from shifting in to gear.
If no gear works at all, I doubt all the bands failed simultaneously, so...it could be as simple as a bad solenoid, or you could have much more serious mechanical problems with the torque converter and/or related components.
EDIT:
And actually, I probably shouldn't be so casual using "lock up" in regards to the torque converter since it can be misconstrued. It's not really a matter of the converter's lock up function engaging so much as it's an issue of the stator clutch engaging to put the vehicle in gear.
Anyway, check the items mentioned above, if you're still having problems with no drivetrain power at all, you may want to start checking the torque converter and the stator clutch in particular. What you're describing sounds a lot like the clutch may have broken. They're pretty damn fragile when they get older, especially when shock loading is involved (ie. sudden hard acceleration/application of power).