RICE -- Rest, Ice, Compression, Elevation.
Really, the only way to heal a sprain (which is a stretch or a tear of a ligament), or a strain (which is a pulled muscle) is to rest. Continuing to exercise will only irritate the affected area more, and lengthen the healing time.
Sprains can be very serious injuries, resulting in a complete tear of the ligament. If you continue to have trouble walking or moving the joint, or the swelling has not gone down, see a doctor.
You can also take over the counter anti-inflammatories (NSAIDs - Non-Steroidal Anti-Inflammatory Drugs) to help reduce swelling and control pain. Common ones include ibuprofen and Aleve.
You can help to avoid sprains and strains by stretching thoroughly before and after exercise, and being aware of your body and its limitations.