If you wish to change High Contrast Theme back to normal in Windows 11/10, please read this article. High contrast theme is an Accessibility feature to help visually impaired.

The key to a great picture lies in contrast ratios but a higher number isn't always betterWhether you already have a television or you’re in the market for a new one (or projector, camera, or any ...

1] Through Control Panel. To enable the high-contrast warning message and sound, follow these steps: Open Control Panel. Go to Ease of Access > Ease of Access Centre.