My anke feels sprained for two weeks now. What could it be?

Varies . Sprains can be graded based upon the severity of the injury as 1,2,or 3. Grade 3 sprains may take several weeks to fully recover from. Consider being seen just to make sure it is not something more serious, such as a fracture.
Sprained Ankle. It could be a sprained ankle. It can easily take several months to recover even w/ pt from a sprained ankle. Hopefully yours is not that bad. I would recommend that you try to walk on it normally and avoid sports for now. A protective brace can allow early sports in some cases. Range of motion exercises with help speed up recovery. If this does not relieve your symptoms see your local podiatrist.
Doctor can evaluate. A simple ankle sprain should be better after 1-2 weeks. If not better, a primary care doctor, sports medicine doctor, or orthopedic doctor can evaluate to see if there is something more serious than a simple sprain. X-rays may or may not be needed at the first visit. One should avoid using the ankle too much until the doctor is able to examine it.