Lightroom Classic not finding files

how come when i upload photos to lightroom, edit them, and then save them to another file I cant go back and reupload them to lightroom to edit them further or just open them up from the previous upload to lkightroom.  It says can not find file and when i try to reupload them to lightroom it says they are already in the library but I cant access them. its the dumbest thing ever especially for such a high powered program. please fix this so i can get my work done easily. thank you

By @mikec65402127

This sounds like the photos are in Lightroom Classic, but not where you think they should be. Please follow all four of these steps in order, and see if you can find your photos.

1. In LrC, click on All Photographs on the left hand side of the Library Module under Catalog
2. In LrC, turn off filters (Ctrl-L once or twice)
3. In LrC, Expand all stacks (Photos->Stacking->Expand All Stacks)
4. Using the Lightroom Classic filter bar, search for at least one of these photos by file name.

Also, it helps for clarity and proper communication, you do NOT "upload" photos to LrC, you "Import" photos to LrC. You do not "save" photos to another file, you "export" photos.

and then save them to another file 

By that do you mean Export, or do you actually mean Move?

If you move them, do you accomplish that within LrC or outside if LrC?