I had created a number of subfolders under my inbox and accidentally hit the “Collapse” button so that they all disappeared. When I tried to re-create some of these I received massage that folders with that name already existed. Can I retrieve the collapsed folders and if so how?
Just click on the left arrow!
Many thanks from an old fella. Feel foolish but learnt something
Don’t feel foolish. We’ve all been there. 
Suggestion:
Contact your local library about PC courses after covid-19.
Also check if there’s a U3A near you. They often have a computer group. A good source of technical backup too.