Hi Julien. I'm Greg, an installation specialist and 9 year Windows MVP, here to help you.
You should be following this tutorial to move User folders: https://www.tenforums.com/tutorials/1964-move-u...
They're idea to move to the hard drive since programs are affected by the speed differential but files are not.
If you moved a User folder into the wrong folder or a whole drive, then move it back to default from the Location Tab on the User folder as shown here: https://www.tenforums.com/tutorials/23504-resto...
BUT do not tell it to move the files too. Say NO to moving them and instead copy them back manually or it will dump all the files from the drive into the restored default User folder.
If a User folder ever disappears, it shows in Option Two how to recreate it. They are never lost, always can be recreated. It just takes patience.
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.
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