I'm a little odd when it comes to my theory on how Tutankhamun died. . . it's actually a bit of a mixture of many theories.
See, I belive Tut was murdered. I'm not totally convinced that he died of 'gangrene'. I mean. . it's possible, but the guy was the Pharaoh of Egypt. Wouldn't they have caught an infection LONG before it turned into gangrene? It just doesn't seem plausible.
Someone mentioned that a bone fragment was found in Tut's skull. That is true. My belief is that it was broken by the embalmers during mummification. . but it had been loosened before. A blow to the back of the head (rather from a fall or an actual blow), causes the brain to move forward, hitting the front of the skull, usually breaking small peices of the bone right above the eyes.
Tut suffered from Klippel-feil, which makes mobility extremely hard. He could have turned his head slightly, but to look behind him, he would have had to move his entire torso. Klippel-feil paitents also usually have scoliosis. Canes have been found in Tut's tomb, and many of them were clearly used. If you see most of his paintings. . .you'll most of the time see him with a walking stick of some sort.
My personal theory is this - Tutankhamun was struck in the back of the head by a murder attempt. I read somewhere that he lingered for a while after reciveing the blow. I think they estimated about 3 months (how they figure that, I dunno). That would have been a perfect time to hunt down a possible murderer. Yet, tramua to the brain is NOT an easy thing to get over. Even if he had lived, he probably would have suffered migranes, even more problems with his back, etc. . . I think he probably officially died from an anurism (can't spell xD). I'im pretty positive that once Tut went unconcious, he never woke up. They shaved his head, for one. Preists, doctors don't just shave the Pharaoh's head. He probably wasn't awake to give permission, and the doctors were desperate.
This, however, is just my opinion, and very few people agree with me. IT seems plauseable to me. . .but I love reading others theories
now let me explain my theory............Ay and Haremheb decide to take the throne by killing tuts dad Akaten so they kill him. but he has heirs to the throne so they kill Smenkhkare after that tut comes to the throne,the last in the line. so Ay uses his influential powers to strengthen his claim to the throne, so Ay and haremheb kill tut well he sleeps. now this is the part where Ay and Haremheb clash. but sly Ay marries tuts wife so he can rule, and because tut has no brothers (because Ay and haremheb killed him); no one can stop Ay, no oppisition. Haremheb does not come to blows with Ay because he knows that Ay will die very soon, so he waits. and then when Ay dies he takes the throne and no one argues with him because theres no Royal family left and he is the leader of the army. but to cover suspition he wipes out their entire line on the list of Pharaohs.
Ay was always behind tut pulling the strings, sumthing he could never do with Akhaten but haremheb was always there waiting for when the time was right, waiting for when there was no one to stop him, no civil war 
