R451 is locked and i don't know the lock code

What is your mobile and model ?
If you forgot the security code you have to reset you mobile. Its the only way to use your mobile again. After resetting you can enter a new security code again.
If you use nokia or alcatel mobile means just visit here Simpleunlocking.com for the master reset code service and get the reset code........

Try code from service provider..........

As I know the lock code is 12345 if you don't change it.
Or you can Reset it and remenber well the new lock code.

electronics wholesale

Sorry i don't know the code to unlock it from 3 Network lock,You can get the Code from Online site and Unlock it,you can get the Unlock code from the site Wickedunlock.com
and Unlock it from Network Lock.

To change your code:

1. Remove the inner cover plate from the lock.

2. Locate the small round reset button near the left side of the circuit board (Red or Black).

3. To program, press the reset button once, then enter your 4-8 digit code on the exterior keypad, then immediately press the middle lock button on the exterior keypad. You will hear a beep. This signals that your code has been accepted.

4. To enter a second code, follow the same procedures as in step 3, but this time press the reset button twice then enter your code.

hope this helps

John

try this link. it may help you,
http://twilightwap.com/mobile/secrets.asp?phone=Nokiagoodluck

If your mobile phone displays Phone Restricted with an Undo option and selecting Undo results in an Enter Restriction Code error, your mobile phone is Network Locked. This means your mobile phone has been restricted for use on one specific network and a Restriction Code or Unlock Code must be entered before the phone can be used with alternative networks.You can get the Restriction Code at here
Onlinegsmunlock and Unlock it from Network Lock,Then Nokia Mobile Mostly asks for restriction code!Your Phone Brand,model,Network,Country it locked you need to specify it...

There are two types of Sim lock ,
1. Sim locked to Network
2.Sim locked with security code,
if the Phone locked to Network means get the Unlock code from here
Superunlockcodes and get the Free unlocking instruction from here
Mobileunlockguide and Unlock it...
If it locked to security code means get the master reset code from service provider reset it.

are you going to change your lock or security code?if you wish to changer it,or are you trying to put a security on your phone.(* the default code is 12345)

just go to settings > security > lock code and enter your code (there's an option if you wish to change or edit your code.

good luck...