I suggest that you get to your vet asap ... most likely if your chameleon fell and broke his legs there is more going on ... such as MBD. I have been treating my chameleon for MBD after he fell and broke all four of his legs. They have since healed (except for one that is still splinted). If you don't splint their legs you run the risk of "non-union fractures" which means the bone ends don't touch and heal back on themselves... leaving for a permanently unstable leg, which would be very bad for these guys seeing as they are so dependent on climbing.
When hermie broke his legs (there are a couple threads in the health clinic entitield hermie something or other that plot his progress and treatment), the vet put him on antibiotics, pain meds for a week and liquid calcium supplements twice a day that is still be continued. We also had to confine him -- he was not allowed to climb at all (as he was most likely going to fall and rebreak his legs, cause further damage etc). I thought that he would never adjust to it, as he is very tempermental, but surprisingly he adjusted VERY well.
He required a lot of care, as he also stopped eating on his own during this time, and had to be handfed baby foood from a syringe and worms that we dropped into his mouth, and it was hard to thermoregulate, because he had such troubles moving. I was lucky in that hermie will drink willingly from a bowl.
I set up a tank for him (which is not usually a good idea for chams but we needed a small confined place) that was a 20 gallon. We put layers of towels in there for him, that were not flat, but rather just sort of flown in there so that he had something to grasp, and i put some rolled up pieces of paper in there for him to grasp onto when he "walked" around.
good luck!