[Speedskater]

 I have about 50 GB of old data files on an XP hard-drive. The Windows 10 'File Explorer' shows the correct total drive usage, but only displays a small percentage of the data files.
Is there a trick to make W10 see all the data files? Or an aftermarket program?

[srb]

It could simply be that they're marked "hidden" in which case you can simply go to View > Hidden items (checkbox) in Windows Explorer.

If that's not it there could be file corruption on the hard drive.  You can go to a command prompt and run
chkdsk x: /f
where x: is the letter of the hard drive.

If that doesn't fix it you may have to try some file recovery software such as EaseUS

Steve

[Phil A]

I use EaseUS if I have to.  I have had situations where the hard drive just had an error and right clicking and tools fixed the issue.

[jpm]

I always used Ontrack Easy Recovery Pro, but haven't needed to in a long time - touch wood.

http://www.ontrackdatarecovery.com.sg/file-recovery-for-windows/

Depending on the nature of the problem, anything you write to the disk may overwrite data you're trying to recover and make it harder to get.  My first step is always to remove the drive from the host system and attach it to another computer via USB adapter. You may find yourself able to read the files fine and be able to copy them off. If not, you can run recovery software without writing any new data to the drive you're recovering from.

Look for USB SATA or USB IDE adapters as appropriate for the drive - https://www.newegg.com/Hard-Drive-Adapters/SubCategory/ID-3022?Tid=161009

Recovering the data can be a multi day process and you'll need space to copy the recovered files too as well.

Good luck!

[Speedskater]

It could simply be that they're marked "hidden" in which case you can simply go to View > Hidden items (checkbox) in Windows Explorer.
....................................... .................................
Steve

That's it ! They were hidden. Never thought about ordinary data files as being hidden. They were not on the old XP machine.

Thanks

[srb]

You can remove the Hidden file attribute

1.  Select all of the folders and/or files (Home > Select all or Ctrl + A)

2.  View Properties (Home > Properties or Ctrl + Enter)

3.  Uncheck the Hidden attribute checkbox

4.  Click OK and confirm that changes are applied to selected items, subfolders and files

Steve