How much would it cost to repair the camera on iphone 6s?

my iphone 6's camera and flash stopped working randomly. When i try to access them it doesn't work and the screen is just black. The version number is 11.4.1

I have no idea what might have caused for my camera and flash to not work. Before it stopped working there were several times when the camera would take long and the screen would just be black but it always worked a while. until recently about a week ago, the camera no longer works and I don't know why. I have tried restarting my phone several times and updating it but it still does not work.