I am assuming that you are talking about a vaginal tear. In what way has it not healed? Is it bleeding? Is it swollen and sore? Again, assuming that you had stitches, those should have gone a long way toward healing the wound. If you had sex too soon afterward, you could have reopened the tear or slowed down the healing process. Also, since 4th degree tear extends from the vagina to the rectum, bowel movements may cause problems. Taking a stool softener or laxative will help with that issue as will hydrating well and having a high fiber diet to prevent constipation.
Most doctors have follow up examiniations to check and make sure that the wound has healed properly. If there was no follow appointment, I suggest you make one with the doctor and tell him or her your concerns.