screen and light detector features

1. how to fix the opened screen
2. when I make a call it usually will turn off the screen when it detect an object near its light sensor but mine is like it error so it turned always turned off like when I tapping the screen it turned on for a glance like 1 tick and then turned off again
3. and usually when I tap my finger near or on the fingerprint sensor it's show the fingerprint icon and then I can put my finger to scan but now it's not, I need to click the power button

that's all sorry if this confusing but I hope u can fix my problems thank you so much <3