Hi, I'm Ashik. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP
What is the model of your phone ? When did this problem start ?
It is possible that the android system files are corrupted. We may need to do a factory reset which will delete everything from it. So first, connect it to your computer and backup all your photos and files to your computer.
Then try booting the phone into Safe Mode and try some fixes. Turn off the phone. Then hold down the Power button and when it turns on, release the power button and immediately hold down Volume down for 20 seconds. Does it work in Safe mode ? Please let me know and we can continue.