When I reopen a project, There are missing files. For example, maps, textures and blueprints are missing

I Have had this problem 3 times now in a few days. First I did the two tutorials “building a side scroller w/alan noon” exactly and had them working perfectly in version 10. I saved all my work like normal. Closed the editor. Next day I loaded the project and the BP dude Blueprint was missing. So I rebuilt the blueprint. but it wouldn’t let me save it. It Says it only partially loaded the files. I checked externally, in (file exporer) and it lists the assets in the content folder. But wont load them in the editor. So I abandoned that project started a new one.

Today the new project I started did the same. My Level map didn’t and won’t load. As well, there are missing sprites and texture files. Same issue. I don’t want to do anymore with this until I know I don’t have to keep doing the same work over and over again.