A torn ankle ligament is a sprain. These are graded 1, 2, or3 and the healing time is longer the more severe a sprain. Grade 1 you may return to all activities in a day or 2. Grade 2 may need crutches or a brace for a few days and avoiding sports for a few weeks. Grade 3 may require a longer period of crutch use and a walking cast or brace for a 4 – 6 weeks. A fibular “twist” fracture which is completely stable is still usually protected with a walking cast (often removable) for about 6 weeks to avoid displacement even though it may not hurt.
There is a special kind of ankle sprain called a high ankle sprain which is tearing of a different ligament. This type of sprain can require prolonged casting or even surgery and usually ends the season for an athlete. This can be diagnosed by your orthopaedic surgeon or other expert musculoskeletal provider.