Could someone please help me!

I am editing a movie in movie maker on my windows 10 computer and every time I try to remove a piece of video or try and split the video, WMM freaks out and deletes everything with only a few snippets of video left which are unplayable.

I also can't move anything around. The movie is only 5 minutes long but I want it to be 3.

It was working before but stopped working.

I've tried rebooting movie maker and my PC but it is still not working.

Please help!