If your phone stops working or responding like it used to, restart it to get back on track.
To restart, press and hold the Power button until a Slide down to power off message appears on-screen, then swipe down. (It usually takes about three seconds for the message to appear.) To turn your phone back on, press the Power button.
If that doesn't work, press and hold the Volume down and Power buttons at the same time until you feel a vibration (about 10 to 15 seconds), then release the buttons. Your phone will restart automatically.
Your phone may vibrate as soon as you press the Volume down and Power buttons because it's changing your ringtone to vibrate. Wait to release the buttons until you feel the second vibration 10 to 15 seconds later.
If you don't let go of the buttons immediately after the vibration at 10 to 15 seconds, your phone may show a black startup screen instead of restarting normally. If that happens, try pressing the button combo again.
Not all phones restart this way, so check with your phone's manufacturer to find out how to force a restart.
If your phone has a replaceable battery (it's often under your phone's back panel), you can also restart your phone by removing and reinserting the battery, and then pressing the Power button to turn on your phone. The date and time may be off after you restart this way, but you can fix that by swiping over to the All apps list from Start , then selecting Settings
If restarting your phone doesn't fix the problem, try resetting your phone.