If your mobile phone is slow or in any other way doesn't work or respond as well as it should, it may help to restore the factory default settings. This deletes all configurations you've made in your mobile phone.
Find " Factory data reset"
Slide your finger down the display starting from the top edge of your mobile phone.
Press the settings icon.
Press Backup and reset.
Press Factory data reset.
Restore factory default settings
Press Reset device.
Press Erase everything.
Wait a moment while the factory default settings are restored.
Follow the instructions on the display to set up your mobile phone and prepare it for use.