Deleted Timeline

I need your help. I dont know how i did that but nearly 15 minutes of my timeline got deleted. I dont know how but i need any help to get them back. Nearly 10 hours of editing are wasted 😞

I tried to go back but i must saved or autosaved it to often. I tryed to "go back to the last version" and i dont worked.

You have any ideas?

thank you!