Huawei p9 can no longer adjust color temperature?

Have a Huawei p9 and suddenly the color of my phone has changed - that is, it has a blue tone. When I wanted to look at the ad I saw that there was "Color temperature in blue mode not available" what is this, why is that suddenly and more importantly how do I change it?

Probably, better to back up your data.

Thanks for the answer but not very helpful. By now I found out what it was. There are in the quick accesses a button that means "spare eyes" never seen and probably accidentally operated? Problem solved

Very good, yes that can be good that is the blue light filter, I have always activated with me.