The iPhone “iPhone” could not be restored. An unknown error occurred (1015)

Hello Everyone,
I need help on an iTunes error. The problem occurred after I updated my iPhone’s version. I am given this error code 1015 on iOS 5.0.1 Restore iPhone 3GS. I wanted to open my iPhone but it prompted me to connect to iTunes.
I did the instructions and then it started restoring. In the middle of the process, the said error pops up. I was given a link wherein I could find a solution but I have no idea on what to do after that.
I really need your help on how to fix this. I feel so hopeless whenever I see this pop up – “The iPhone “iPhone” could not be restored. An unknown error occurred (1015). Please help!
Thanks.
