Frost free hose bib not working

I have a frost free hose bib that worked fine approximately 1 month ago when it was last used - today I tried to use it and although the handle turns out, no water comes out (and temperature has been above freezing for the last month) - several questions:
1) What could be wrong?
2) Is there a fix that can be completed without replacing the entire hose bib? And if so, what is it?
3) If the hose bib needs to be replaced, is there a good solution that does not involve soldering (water lines are copper - hose bib water line is very close to wooden flooring material and between wooden joists)?

loosen the packing nut behind the handle and unscrew it further.
The washer is jammed into the seat.
Btw shut off the water 1st.

Don't close it so hard next time.

what would happen if you close it hard? there are times that it leaks so, I close it hard.

Redwood - thanks. I will try what you sugggest. However, I would guess if it was tightened too hard, it was because of what Gelo30 is suggesting...that is, the water was continuing to drip and I was attempting to stop the water from dripping. Do I have a different issue? Do I need to replace the washer? Or something else? By the way, the home is about 22 years old and I have owned it for about 4 years with no previous issues with the hose bib...after looking closely at the line inside the house, I suspect it may have been replaced by a previous owner.

These frost proof hose bibbs actually have a long tube that extends back into the warm area of the house. It is on that end where it actually shuts off and the long tube drains dry this is what makes them frost proof.

Some times people mistacke this tube draining for leakage and close it to hard. The washer on these is often spring loaded and if jammed in to hard will stick. Loosening the packing nut and turning it out a kittle further will free it.

Of course if it leaks and doesn't shut off it needs repair or replacement.

I'm not much on repairing faucets and valves. It's just a whole lot easier to replace with a new one. Call me lazy I guess. Frost free valves are not soldered to the supply line. At the point of connection, a tee has been soldered into the supply line and a female adapter has been soldered into the tee. The hose bib screws into that. All that you have to do to replace is unscrew the old and screw in the new. You do need to use two wrenches to avoid twisting the supply line, and access is often challenging, but the soldering has already been done. The adapter and hose bib have hex ends so fairly large adjustable wrenches will work on them. You would not want to apply heat to the bib at that point anyway because that's where the guts to the faucet are located.