Turn it off and then turn it on. ( restart)
If it doesn’t work you can always try a Hard Reset.
[quote]''“Press and hold the Volume up button, then briefly press the Power button. Keep pressing the Volume up button. Scroll to the desired language using the Volume down button, then press the Power button. Scroll to wipe data/'''factory reset''' by pressing the Volume down button.”''[/quote]
Or just search for Hard reset (your phone model) and look for videos and tutorials.
I’m almost sure this will fix your problem.