I just went through this last November. Do you still have periods? If so, this is probably normal. If you no longer get periods than your doctor will probably do an endometrial biopsy. This is an office procedure that takes about a total of 10 minutes. Some women find it very uncomfortable others like myself really did not have any problems. If the biopsy comes back normal, then the doctor will probably treat it with a prescription of progestrone. Progestrone will allow the lining to be shed.
I had a surgical procedure called a hystroscope/d&c because I can no longer take any hormones. It turns out that I had a large polyp (non cancerous) removed from the wall of my uterus.
I hope this gives you the information that you need.