I just don't know...

When your ankle sprain
Common reason : suddenly ankle inversion or eversion
Caution : once you have the experience, you'll have 55% to happen again.
(to become CAI: chronic ankle instability)

In 24 hrs
use cold pack to reduce swelling
immobilize the ankle
if you still feel umcomfortable, medication is acceptable

After 24 hrs
use hot pack
restore the muscle strength
(especially the muscles around the ankle)
improve the propriception of the ankle, to reduce the ankle sprain recurrence.