Currently Being ModeratedJan 22, 2013 11:52 PM (in response to mirza_cool)
As per the Apple article TS3694,
Error 1015: This error is typically caused by attempts to downgrade the iPhone, iPad, or iPod touch's software. This can occur when you attempt to restore using an older .ipsw file. Downgrading to a previous version is not supported. To resolve this issue, attempt to restore with the latest iPhone, iPad, or iPod touch software available from Apple. This error can also occur when an unauthorized modification of the iOS has occurred and you are now trying to restore to an authorized, default state.
So, If you're trying to jailbreak, don't, and if you can't get it back to its original state, then consider other options.