Amanda, any wounds will heal in a normal condition.
My guess of why your chameleon did not is because either it was infected or she keep rubbing her nose against the screen.
There are many reasons why chameleon would do that.
But, mostly is because there is something in the cage that does not make her comfortable (cage too small, living condition not right, etc etc). Either way, it is a warrant to investigate.
It's quite sad that it has to come to this.
But, i have seen chameleon that cope without their tongue.
They will just go near the insects and chomp it.
In the meantime, I think you should go to the vet anyway to make sure there is nothing in the tongue that become infected.
I would not be relaxed, yet.
Hanging tongue can also be a symptom of nutrition imbalance (aside from trauma). If this happened to be true, then your chameleon is still in dire need of a vet.
Check
www.herpvetconnection.com for an exotic vet nearby your place.
Good luck! I hope she'll be able to pull through
My grandfather actually.
It's unfortunate because I'm away at school and my grandparents are watching the chameleon for the month. They are young grandparents and very capable of caring for her, they know all about feeding her and supplementing and humidity, water, etc. But they couldn't stay up all night to keep it wet like I would have. So this morning it was dry and on a branch and the filament was so thin and her tongue was like paper so he snipped it off.
She is very happy now.
Also for others to bear in mind - She split her nose/mouth by rubbing it on her cage in July. I took her to the vet and vet said it would heal itself. It did not. I've been putting neosporin on it and another topical solution from kvvet and that didn't heal it either. Her tongue has been pink and healthy but who knows, they could be related, so for future reference if your cams hurt their faces on screen - mine did not heal itself.