How do I transfer all my data from one installation to another?

A couple of days ago I was trying to do something using the registry editor but I have messed up some ownership/permission stuff and explorer just stop working completely; I couldn't use the taskbar, settings, open up a folder, I could only use Run and Command Prompt to open up some things to try and fix this issue but I have somehow managed to mess things up even worse; I couldn't even boot into it anymore as Windows was giving an error saying "winload.exe" is corrupted/can't be accessed. I made a copy of the original Windows folder and tried to copy another Windows folder from a fresh installation onto it to see if the issue would be fixed. After that I could move onto the loading screen after a couple of tries (and replacing the "winload.exe" again from the same fresh Windows 10 copy), but after a few seconds the Windows logo disappears and the so does the loading circle after another 2-3 seconds after the logo disappears. During the time I only have the loading circle and afterwards I can only see the mouse cursor that has the blue loading circle on it and I can't do anything else other than moving the cursor around the screen, which most of the time just disappears after I move it and appears again in the center of the screen when I move the mouse again. I tried using a Windows 10 installation drive to try and fix all the issues I mentioned using the options there and using the Command Prompt but most of the commands on CMD gives an error saying either Access Denied or "Windows Resource Protection Could Not Perform The Requested Operation/Perform The Requested Action". The Startup Repair service also didn't work as it just made me wait for a couple of minutes then rebooted the PC with no visible changes at all. I probably should have mentioned it before but after getting the error with the "winload.exe" I cloned my 480 GB SSD to another 480 GB SSD and tried everything that comes after on the clone I made just in case it all gets worse. Is there anything I can do to at least transfer all my data (user data, installed apps, customized things like my desktop wallpaper) to another fresh Windows 10 installation or fix the current one? I would greatly appreciate if I could  instead transfer my data from one installation to another but assuming it is not, I would greatly appreciate if I could just fix the current one as well. (I am posting this as I encountered many errors and couldn't working fixes or anything about them at all from the very beginning so I decided to explain all and try my luck here instead.) In the case there is nothing that can be done like I want, I wouldn't mind another way that I couldn't think of either.