Nokia C5-03 Format Soft/Hard Reset to Factory Settings.

Cull from-http://cellphonerepairtutorials.blogspot.com/2011/02/nokia-c5-03-format-softhard-reset-to.html

Nokia C5-03 Soft Reset:
This will not harmed your data . Soft reset only restores .ini files from Flash ROM on board memory of your Nokia C5-03.

1.). Dial *#7780#

2). Press Ok/Yes

Nokia C5-03 Hard Reset
This will delete your data and installed applications. Hard reset will restore your Nokia C5-03 to default factory setting.

1). Turn off Nokia C5-03

2). Take out the battery and reinsert it, turn it on

3). Dial *#7370#

4). Press Ok/Yes

Nokia C5-03 Hard Reset through button combination.

1). Turn Off the Nokia device

2). Pull out the battery and reinsert it back again, then Power it ON

3). Simultaneously  press and hold *+3+Call Button (green/ok button)