HOw can I retrive a movie I have made in Windows movie maker?

This program is driving me nuts. I have spent months creating a movie in Windows movie maker - all of a sudden this morning I can’t open my project - the error message reads, Not Implemented. Can anyone help me??

windows won’t let me retrieve the movie i started, it says the another user is using movie maker on my computer and I need to shut that one down before I can use my window movie maker, there has been no one else using my computer, can you help and tell me how to fix this problem?