If you ran it flat any distance the stem is prob sucked inside the tire now.....if not you can try to air it up using the above precautions.
Also, as stated above, there is a reason it is flat. Slow leak, punture, dry rotted tube.
If you have never had the pleasure of dismounting these tires I will tell you it is a CHORE.
You have to beat the bead off the rim with a mattock or slide hammer (you will work up a sweat) and then remove the lock ring using tire irons.
You are better off if you have a concrete or asphalt surface to work on.
There are a lot of tricks to making this easier but showing is easier than telling.
If you have the funds I would take it to a truck tire shop and watch them do it the first time.
These tires should ALWAYS be infated in a cage if possible due to the ring flying off.
There are field expedient ways of doing this but ONLY TO BE USED IN AN EMERGENCY.
If you are going to own a deuce you need to know how to do this yourself just in case but at my age I take them to the local "tire Bubba" and pay him for his expertise.
A note on running tube type tires flat. If you run them at highway speeds completely flat they can build heat and catch on fire....been there, done that, got the T-shirt.
That is why you have the fire extingusher on board.
Being a self-reliant type I try to do as much of my own work as possible but you have to pick your battles.
Good luck.