Make sure you properly back up your computer when doing this!
Method 1:
What you want to do is uninstall Minecraft, like completely. Then backup your computer (save everything on your computer, onto another computer). After doing this, you want to completely restart your computer. Delete everything. After your computer has been completely wiped, you then want to download Minecraft before anything else, after doing so check it works. Once you see it does, then take your backed up files and plop them back onto your PC. Hope this helped!
Method 2:
Create a 2nd account on your computer, If you're on mac this is easy. I'm not sure about Windows, but it should be basic. Once doing that, place all "important" files from your main account onto a large captivity USB. Log into your new account and place the files onto it. Download Minecraft and enjoy. I guess you could call this "Migrating"
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~Vanth
P.S Sorry if my grammar is terrible, I'm in Math class trying not to get caught on the forums