How long will it take for ankle bursitis to heal totally?

Depends. Ankle bursitis is an unclear term. There is an achilles bursitis. If that is what you have, nsaids (topical or oral), therapy, even bracing may be needed for short term. This can persist for up to 3 months.
It depends. How long has it been going on. What type of treatment are you receiving, how did it occur?