dont know passcode can i unlock phone some how?

If you lose or forget your passcode, you will need to perform a factory restore to remove it.

http://support.apple.com/kb/HT1212

Do as the manual says to do and restore the iphone.

Pull up itunes and make sure itunes is updated

Plug in your usb to computer...do not plug into phone yet

Press the power button and swipe to power off-do NOT let the phone shut down and quickly press the home button and hold onto the home button while connecting usb to iPhone and continue to hold the home button until you get connect to itunes show up on your phone.