Hi there. Looks like your friend has had a ligament injury to the ankle. The pop sound she's heard is suggestive of the same. For my patients, if the swelling was really bad to begin with, alongwith inability to bear weight on the affected lower limb, i would firstly put a plaster cast for 4 weeks for the ligaments to heal and then remove it and start them on ankle exercises. If her pain and edema/ swelling are not so bad then compression/crepe bandaging should be sufficient enough. Rest, elevation of the involved leg and ice pack application are the additional supportive measures. So for your friend whaat i would advise is that if she has had this injury few weeks ago she should take rest for 3-5 days, avoid putting weight on the lower limb involved, minimum ambulation only to the bathroom if need be, and ice pack application locally. If it does not subside within a week she should do x rays and get herself checked.