Cant access files from external HDD with OS installed

Hey guys

So I need to format this HP laptop with 170gb worth of backup files.

I have a case that can turn internal HDDs into external via usb 3.0 cable. So I took out the HDD from the laptop and plugged it to my PC using the usb case that I just mentioned.

My plan was to copy those 170gb in my PC, then put the HDD back in the laptop, do the factory reset, take out the HDD, again plug it on my PC, cut and paste the 170gb back to the laptop's HDD, and then put the HDD back in the laptop.

But this is what happened:

When the laptop's HDD was connected to my PC with the case via usb and I was trying to find the files to copy, I couldnt access the user's folder (the 170gb backup folder was inside documents folder so to get there I needed to enter to the user folder first) It was like loading forever, I even left it there for half an hour and never showed any folders.

I gave up, took out the HDD and put it back on the laptop. Everything booted correctly but now I couldn't open or copy any file!! I tried to copy one image from one folder to another and a message popped up saying this:

"An unexpected error is keeping you from copying this file. If you continue to recieve this error, you can use the error code to search for help with this problem. Error 0x80070490 element not found"

This happened with EVERY file i tried to open, copy or move

I searched it up and the solution that I found was to run an Error Checking to the drive via right clicking Local Disk, Properties, Tools tab, and then "Check".

It took some time, the system rebooted and now I cant even do anything! I log in and then from the desktop I cant access anything. The programs and folders in the desktop show up but when I try to open any it freezes, shows a black screen for like one second and then takes me back to desktop. Cant even open the start menu or the file explorer via Windows+E keys. The file explorer kinda tries to open, it says "just a moment" and then after 4 seconds it closes, black screen, and back to desktop.

Please help me guys :( Im about to cry I dont wanna lose those backup files, the laptop its not even mine and it has important data from the owner who is an architect. I just need that 170gb folder...