I want to be a “contributor” to the blender community, so here’s a stab!
If you see your meshes faces fine in object mode but go to edit mode and the faces are gone, you may have “hidden” those faces and forgotten about it (like me).
In edit mode hit CTRL+A to select all faces of the mesh in edit mode (even though you can’t see them) and hit ALT+H to un-hide them. Hope this was helpful. I was about to freak out before I tried this and presto…