things that I have drawn cannot opne

This is not first time. After I finish drawing, then I shut down my laptop. But second day, when I open it, it will become blank. However, the layers that i draw still have. Why?

After I unlock it, it still remain the same

It looks like the layers are locked. Click on the little padlock on each locked layer in the Timeline.

It also looks like the layers have drawings at the last frame, your cursor is on the first frame.