I am cooking mutton in a frying pan but it's not getting cooked properly. I don' have a pressure cooker too. What should I do to cook it?

Is the mutton whole, and are you trying to fry it? Or is there stock, etc? I have only cooked mutton in Lancashire Hot Pot and it is cut into cutlets, put into a casserole (with other ingredients) has stock added and cooks for 2.5 hours @ 325 covered and @425 uncovered. Which is quite a bit of cooking for smaller meat cuts. Possibly you need to make your meat smaller and give it more time. Or can you put it into the oven?