my son decided to reset a passcode to get on his phone and does not remember it. it now says iphone disabled connect to itunes, how can i fix this

See the instructions in If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

No. If you are certain that the phone is off before you connect it to the computer and you then hold the Home button while connecting it to the computer, it should display that screen fairly quickly.

If you are sure that you have done it correctly then another method to try is the following: https://www.imore.com/how-to-iphone-ipad-dfu-mode#ipad