How to heal a swollen finger back to normal? Been a couple of days already,

Motion. If this is secondary to a trivial injury, continued motion and elevation should suffice. If symptoms persist, over 2-3 weeks, it will need to be evaluated by a hand surgeon.
Jammed. Make sure it's not cracked first, if not, motion by flexing-extending the finger as tolerated to minimize more swelling. Tylenol (acetaminophen) as needed.