How do I turn back on color display on my IPad

Hi Shambala2014, thank you for posting in Apple Support Communities.

Can you please check in Settings > Accessibility > Display & Text Size and check that 'Smart Invert' and/or 'Classic Invert' is turned off which may be the cause of your issue as per the following link:

https://support.apple.com/en-au/guide/ipad/ipad9a246013/ipados

If the screen colours appear to be distorted or unnatural, you need to check some key Accessibility settings that are intended to compensate for specific colour-vision issues:

Settings > Accessibility > Display & Text Size

Ensure that all settings enclosed within the red box above are switched OFF/Disabled.