Recovering files from corrupted User Account?

I'm trying to get my in-laws laptop back up and running. It's so painfully slow to boot / load anything, and for some reason the start menu won't even pop up (Though thankfully the run command appears quite quickly with a Win+R!)

Every time I log in it says it couldn't log in to my account. So all the music, photos and documents directories show as empty. Seems it's giving me a temporary profile.
So I've gone in to the Registry Editor, here: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
found one of the profiles has .bak after it, and renamed it back so the correct profile is now listed. (As described here: [FIXED] We cant sign into your account. Windows 10 Temporary Profile Issue - YouTube
Problem is, the next time it reboots it does exactly the same thing.

Is there any way of pulling the files out of this user's directories? Perhaps if I pulled the drive and just plugged it in as an external drive?
I've got no problem wiping this whole machine and starting again, looks like that's exactly what it needs, providing I can pull the photos and music collection from it to restore when I'm done!

Any help appreciated!

I would try Kyhi's bootable rescue media here - Windows 10 Recovery Tools - Bootable Rescue Disk

I've used it twice on other computers to rescue the data to an external storage before tinkering with or nuking the OS. Download the iso and burn to usb, then boot to it. The desktop in the tutorial will appear and you can use File Explorer to, hopefully, navigate to the folders that you want to retrieve. Good Luck.

Thanks for your reply! I guess I should have tried this first, but before going to huge effort, I found a SATA-USB adapter and tried plugging the drive in to my PC - it did actually let me in to the user accounts folders! (What the hell is the point of passwording it?!?!)
So I've been able to copy the data off!