iPhone 4S iOS7 passcode problem I just recently updated my iPhone 4S to iOS7 and it was pretty much okay at first.

After I turned on the passcode for lockscreen I am now unable to unlock my iPhone. I was so sure I put the correct passcode for it because that is the only passcode I used in my iPhone for years. How can I unlock my iPhone?
When you set the passcode, you are required to enter it twice to ensure that you don't make a mistake - if they don't match, you are requested to try again.  If you are unable to use it to unlock your phone now then either you made the same typo twice when setting it, or you are not recalling accurately what you set it to.  Either way, you will need to restore the phone via iTunes to rectify it.