why has my phone gone negative

[John Burnett1]

I dont know what i did, but my phone has gone negative

 

[Tim1954]

Hi John, welcome to the forums mate.
Usually of you post, it's helpful to include the device and software as a bare minimum for us to go on.
In any case, I'll guess Samsung galaxy...
Settings... Accessability... Vision... Scroll down to the bottom to find negative colours.
In devices with home button, you can set it up so three quick presses of the home button reverses colours...

 

[Tim1954]

Ha! I have just discovered in my S8 that if I press the power and volume up buttons simultaneously, I get the negative screen. I suspect thats what you did....