You'll have to make an effort to remember the password, the security system of the iPhone is so high that if you do not put the correct password can not use it.
This is due to the large number of thefts, and from the iOS System 7, you can format it, but I requested the key and the Apple ID with which she cease-device to use it, so it's useless, the key.
I think apple or services can remove these keys, so many cases of theft.
Browse over your notes or make an effort, without that key will not help you.