toilet tank
 

suddenly no water going into my old toilet tank. the water valve is open. what happened?

Float is stuck in the full (up) position?
Clog in the water fill valve?
Water shut off to the valve?

Is it frozen under the floor, in the outside wall

Not in Ft. Lauderdale...

Turn off the valve then turn it back on.
If the tank fills one time then goes back to not filling and you have a Fluidmaster fill valve then replace the fill valve and supply line its shot.

Also another possibility is that you have a Watts Floodsafe supply line and it has nuisance tripped. Get rid of it and install a regular braided stainless steel supply line without the Floodsafe feature. Trust me you are lucky it didn't fail a different way...