Q: changing passcode

Hello

I am not sure I follow but I will give you a few options to take care of the issue that you may be having.

If you log into icloud.com, you can enter Lost Mode, which will let you put a passcode on it.

iCloud: Use Lost Mode

http://support.apple.com/kb/PH2700

If there already is a passcode on it, you cannot change it. If you cannot access your iPhone and iPad because of that passcode to get in, the only option is to follow the article below to put it into recovery mode and then restore it using iTunes

iOS: Forgotten passcode or device disabled after entering wrong passcode

http://support.apple.com/kb/ht1212

If it is just a matter of you forgetting your Apple ID password, you can reset it by following the steps in the article below.

Apple ID: If you forget your password

http://support.apple.com/kb/ht5787

Regards,

-Norm G.