If you have a Grade I or Grade II knee sprain, your doctor probably will recommend that you follow the RICE rule:
Rest the joint.
Ice the injured area to reduce swelling.
Compress the swelling with an elastic bandage.
Elevate the injured knee.
Read more here on How Do You Treat A Sprained ACL Anterior Cruciate Ligament.
https://www.health.harvard.edu/pain/knee-sprain-
Youtube video on How Do You Treat A Sprained ACL Anterior Cruciate Ligament