Camera black screen + flash light doesnt work

Hello. i have a problem with my iPhone 8. Then I open a camera or a snapchat, I can only get a photo with a front camera( I mean selfie camera :D) but then i open back camera ir shows me only black screen and its like laggy. also the flash light doesnt work in the back too. its not even broken. any ideas how to fix it? i have tried all of the resets. im out of ideas...