If I were you, I'd power my iPhone all the way off by long pressing its power button and then turn it on again. This might help. If not, the next thing to do would be to go into the Settings app. Under the General tab, there's a section called 'Reset Device' (or something like this). If you go into that section, there's a button for resetting your device's settings. This will clear your settings but not delete your apps. (You'll need to re-enter your WIFI password(s) after using this…) Clearing out your device's settings could also help with your problem.