Lastly I suddenly turned off my compiter while I was working because of a problem with my battery. WhenI turned on again the PC The project couldn't be opened becase of an unknown reason. I tried many ways autosaved project , XML repair but nothing helped me.Well auto saved project didn't helped me because the last project was saved days ago. I did the project again but this tought me for the next time.I changed this settings: Autosave every 10 minutes and Maximum autosave project To 50.So I will never miss a project again.