The factory setting formatting password defaults to 12345. If you have changed the password and then forget it, you can only restore the factory settings by hard formatting.
The hard-block method is as follows:
Take Nokia c5 as an example
1. When the Nokia phone is turned off, press the dial key, * key, 3 Numbers and hang up keys.
2. Press and hold until the Nokia power-on logo appears on the screen.
3. When fprmating/ appears on the screen, release your hand and start the hard grid.