How to Find HP DeskJet 2640 WPS Pin
The Internet Service Provider that you subscribe provides a network password.
Search for this password on your wireless router.
The password is labeled Wireless Key or WPA2 password, or WEP key.
In Windows
Ensure that the printer and the Windows computer are connected already.
Right-click the wireless network tray icon on the taskbar.
Open the Network and Sharing Center option.
Click the Change Adapter Settings option.
Double-click your HP Deskjet 2640 wireless setup network name and click Status.
Expand the Wireless Properties menu and click the Security menu.
Select the Show characters check-box and the wireless network security key appears on-screen.