GUI doesn't display - Process won't terminate normally

[Maq47]

I've had this problem for a year now, but just now got around to posting about it. I used to have VirtualBox installed and working fine at one point, but uninstalled it for a couple of months to make room on my hard drive. During that 2-month period, I tested around 6 different Android emulators, such as Andy OS, Nox, Bluestacks, MEmu, and Remix OS. I had a corrupt Nox installation at one point, and had to remove the files and registry entries from my computer manually because the uninstall process would hang. Upon reinstalling VirtualBox, attempting to run VirtualBox.exe results in no GUI appearing, but the process starts in Task Manager. Ending task via Task Manager does nothing, and doing taskkill via command line results in an access denied error. I have to use a program called LockHunter to end all of the program's child processes at the same time in order to close the process.

Virtualization is enabled in BIOS (no BIOS settings were ever changed, and VirtualBox was working before), and Hyper-V is disabled, although it was enabled at one point while trying to find a way to uninstall the corrupt Nox. Virtual Machine Platform is actually disabled in Windows Features, although I assume it is for use by the OS for its older built-in VM support, and irrelevant to VirtualBox. I am at my wits end here. Can anyone help?

[BillG]

If I was in your position, I would have done a clean install of Windows long ago after all that horsing about.

[Maq47]

I have hundreds of gigabytes of important files on my hard drive, and no way to back them up, so a clean install is out of the question.

Edit: I also use Authy, and will lose access to any accounts with 2-factor authentication if I reinstall. For some reason, the Cloud Backup option resets itself every time I restart Authy.

[scottgus1]

I have hundreds of gigabytes of important files on my hard drive, and no way to back them up

A little bit of IT advice:

Find a way.

Hard drives, motherboards, OS's all fail. If the data is important, back it up. And do so in a way that is reliably restorable. 2-terabyte USB drives are a hundred dollars US and Macrium Reflect Free is, well, free. Make disk images if the data depends on your specific OS.