Where are my files?

I have 3/4 capacity used in my ex. Drive storing Karaoke and music folders.

Files alphabetical a thru z.

I added more files noticing that files were NOT shown in explorer. Noticed files “U” thru “Z” not shown in window, if I SCAN the drive I can see the files ARE in it.

I added a folder and combined several folders i.e. A thru C in a folder and D thru F in another.

Noticed folders showing up “U” continued combining folders looking for Folders “V” thru “Z”

After closing the explorer for the ext. Drive and reopened NOTHING was shown except ONE Folder!

Still show 3/4 of the drive used. How can I Unhide ( ?) the folders, or do I compress the files?

Don’t know what I did.

ANY HELP APPRECIATED!

Corruption…

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get the data with a recovery software and reformat