Dear, when I set the passcode, it was the first time after a while and the passcode wasn't the one I had set previously.
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And finally I restored the phone in dfu mode. Then I restored my backup and fortunately it didn't ask me for passcode! So my concern was unnecessary!
But a remainder problem: after restoring the backup, all of my data like contacts, text messages, notes, songs, ... are completely restored, except apps. None of my apps are restored, but the default ones like calculator, note, navigation, calender, ....
Can you help me plz?