Hello Curried_1,
Good day! I'm John DeV a Windows user like you and I'll be happy to assist you today. I know this has been difficult for you, Rest assured, I'm going to do my best to help you.
I recommend uninstalling startallback, winareo tweaker and TIW11 first.
Please try the method below if it helps.
Press Windows key+R to open Run then copy and paste the path below to open the old Personalization.
shell:::{ED834ED6-4B5A-4bfe-8F11-A626DCB6A921}
Press Enter
Under Windows default, select Windows or Windows (light)
Restart your computer then set Dark mode again
Kindly let me know if this helps or if you have any further concerns.
Kind regards,
John DeV
Independent Advisor