When you want to learn more about how to use your phone, or if you're unsure how your phone should work, read the user guide thoroughly.
If you have an issue, do the following:
Reboot your phone. Press and hold the power key for about 10 seconds. The phone switches off. If needed, to switch your phone on again, press and hold the power key.
Update your phone software
Restore the original factory settings
If your issue remains unsolved, contact Nokia for repair options. Before sending your phone for repair, always back up your data, as all personal data in your phone may be deleted.