i need to unlock my phone

What do you mean it failed? You were unable to restore your device with your computer? For the device to appear on the computer, it needs to be put into Recovery Mode. Follow the instructions in the support link I provided. If that still won't work, you need to follow the instructions here. If your computer doesn't recognize your iPhone, iPad, or iPod - Apple Support

If you forgot the passcode for the iPhone, you need to restore it. See this. If you forgot your iPhone passcode - Apple Support