[HELP!] Corrupt my Windows 10 profile by using an old theme!

[Nimbi]

Try going here: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\ThemeManager and here: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes

if you can get to the logon screen then try to login having high contrast enabled from the Ease of Access button on the logon screen

These are both very good options, let us know if either of these work for you =)


---edit--

or if one of the other options suggested after these works xD