These simple steps can help in a majority of cases.

Restart your phone

For phones with removable battery: 1. Switch your phone off 2. Remove the battery. 3. After a few seconds, put the battery in and switch your phone on.

For phones with non-removable battery: 1. Press and hold the power button until the phone vibrates and switches off. 2. Switch your phone on again.

Reset the settings

Restore the original factory settings as instructed in your phone's user guide. Example for Nokia N8 and E7:  Select Menu > Settings > Phone > Phone management > Factory settings > Restore.  

Update the software
