A soft reset (turning the device off then back on) is similar to restarting a desktop computer and is one of the first steps in troubleshooting a device. A soft reset won't affect data on the device. It is recommended to perform a sync operation before a soft reset to ensure that all data is backed up.
Press and hold the Power button until the 'Turning off in' screen appears (approximately 1 second) then release. If the device is unresponsive, press and hold the power button and the volume keys (volume up and down) simultaneously until the display powers off then release.
Select Restart (located in the lower-right). Allow several minutes for the process to complete.