Nokia 309 - Manual (Page 86)

Restore original settings
If your phone is not working properly, you can reset some settings
to their original values.
1. End all calls and connections.
2. Select settings and restore factory sett. > settings only.
3. Type in the security code.
This does not affect documents or files stored on your phone.
After restoring the original settings, your phone switches off and
then on again. This may take longer than usual.
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