I have fallen arches but left foot always hurts. sometimes i can't walk on it.inner part at ankle bone is painful all the way down. burns too?

Tendinitis. : Can be treated starting with rest and anti inflammatory in short term and a good arch support in the long term. Don't delay.

Try orthotics: To help stabilize the fallen arches.

Common complaint: Several causes like over weight, tendenitis, poor body mechanics, inflammation are a few.Your best bet is to see a podiatrist ASAP to get some relief.