iphone could not restore. an unknown error occure(1015)

The error 1015 means your phone was hacked/jailbroken before:

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. Very rarely this error is caused by a hardware issue and requires service.

You will need to speak with who ever loaded the hack onto that phone.

As was already pointed out, your phone was jailbroken. Jailbroken devices can not be discussed here per the terms of service.