Black screen

My iPhone Homescreen or wallpaper keeps going black. It does this randomly and later the picture will display and other times it’s black for hours and hours. It is not on “do not disturb” or “sleep mode” it does this on normal settings. In fact I have turned on sleep and off and other options, checked wallpaper settings, but it just goes black after updated to new IOS. Help?! What to do?? It was my favorite background and picture of my lil boy sent to me!