I forgot my iphone 4 password. What can i do to unlock it?

Restore it from backup in iTunes. This will remove the passcode.

Then you'll have to force the phone into recovery mode & restore as a new device:

Turn your phone off. Leave the USB cable connected to your computer, but NOT your phone, iTunes running, press & hold the home button while connecting the USB cable to your dock connector, continue holding the home button until you see “Connect to iTunes” on the screen. You may now release the home button. iTunes should now display that it has detected your phone in recovery mode, if not quit and reopen iTunes. If you still don’t see the recovery message repeat these steps again. iTunes will give you the option to restore from a backup or set up as new. In your case, restoring as "New" will be your only option.

You're welcome.

This isn't working for me and I've tried multiple times. I keep getting message in iTunes to put in the password. What do I do now?

oh my gosh. i love you..lol

Thanks a million, my IPhone is connected to ITunes & restoring my phone.

@wjosten how do you restore it from backup???😕

it wont work on my phone