iPhone 4 update

[Satchi8]

Hi everyone,

I have iPhone 4 and when I connected it to my computer to sync. There was the new iPhone update that I agreed on. It showed me what the new features will be then it said it will take an hour to update. So an hour later I
Check on the status of the update. A pop up window says "Enter the password to unlock your iPhone backup file.

My problem is that I have no clue if I had a password for backup & if I did no way I can remember the password
It was a year ago.

Please if anyone had the same problem or knows what to do. Please write me back.

Thank you in advance