Help! Skyrim quest! Possible spoiler!?

The quest Mehrunes Dagon is a quest started at the museum in Dawnstar. Earlier in the game, I visted there and a dragon attacked (pretty common spots for dragons now) and I tried to help kill the dragon. Earlier in the game I had gotten Dragonrend and was able to help get the dragon on the ground. I went To go kill the dragon and a guard got in my way and I kinda accidentally killed the guard. After that I was being attacked by guards, towns people and a dragon. So now I get to my question. I killed Silus Vesuius because he was doing the most damage. Now that he's dead I can't get inside his museum to do the Mehrunes Razor quest. Soo I have no idea what to do. I cannot pick the lock. It was to long ago and I didn't know it was of importance so I can't go back and load it. I'm on ps3 so I cannot use commands either. Any help?