Hi dumbbell,
I understand that you cannot scan from your Officejet 4620 to your new Windows 8.1 laptop. I will try my best to help you with that.
In this document for A 'No Computer Detected' or 'Connection Error' Message Displays during Scanning are steps that may help you resolve this issue. Your firewalls may be blocking the scan.
If this does not resolve your issue, please tell me the error you are getting when you are trying to scan and what happens.
I hope this help, please let me know.
Thank you,