Why did my screen change color my pictures look like negatives now

It would help if you can post the exact model of your phone. Likely you have managed to change your display settings. With the iPhone a triple click of the home button used to result in the same thing.

Just go to settings, and select “Accessibility” You’ll see a choice for vision. Select vision, then turn off “Inversion.” That should fix it for you. (Note: this is how it works on my LG phone. I imagine it should work in a similar fashion for your phone, too.)

"Depends on your phone and/or o/s. In

Settings

General

Accessibility

Choose to invert color scheme

………

If this isn't correct for your phone/ o/s, you should be able to find where your files are found to fix."

"My phone is a LG K20+. I noticed this this morning suddenly. I tried restarting the phone, but it didn't work.

I read the comments. I found the high contrast and photo inversion buttons in the Vision section of Accessibility (I'm never at this setting, so I don't know how this had happened).

I tried high contrast and it had to take time to change the setting. Everything looked like a white background, no home screen photo (I have a family photo for mine).

Then I undid high contrast and chose photo inversion. That fixed the photos looking like negatives.

However, my homescreen is now at factory default. I've lost my family photo as my homescreen."

Settings, accessibility, color inversion, turn off, make sure it's off,