i forgot my password!

If you cannot remember the passcode, you will need to Restore the device...

Connect to iTunes on the computer you usually Sync with and Restore...

http://support.apple.com/kb/HT1414

If necessary Place the Device into Recovery mode...

http://support.apple.com/kb/HT1808

I have forgotten my password but when I link it to the computer, my device doesn't come up on iTunes