screen time passcode

"If you forgot the [restrictions or ScreenTime passcode] for your iPhone, iPad, or iPod touch, or your device is disabled" read this link --> http://support.apple.com/HT204306 - You can restore from a backup but that backup has to date from before you set the restrictions/Screen Time passcode.

Edit:

If it isn't working then you are not successfully getting it into Recovery Mode. Try again. Hold the power and home buttons down for quite a while to get the connect to a computer display on the device.

click here If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

You put the device in recovery mode as outline in the link, you're not required to enter any code, then you restore to factory settings as outlined in the link.