HP 4620

Does your modem/router have a WPS button?

The printer wants to be added to the network that way.

You hold the button for 2 seconds, make sure your blue wireless symbol is lit up on the printer.

I would reset the printers wireless first:

Turn the wireless radio on and off
The wireless radio is on by default, as indicated by the blue light on the front of the printer. In
order to stay connected to a wireless network, the radio must stay on. However, if you have
a USB connection, the radio is not used. In this case you might want to turn the radio off.
1. Press the (Wireless) button, and then, using the buttons on the right, scroll to and select
Wireless Settings.
2. Select Wireless: On/Off, and then select On to turn on the radio, or Off to turn off the radio.
Change advanced network settings
CAUTION: Network settings are provided for your convenience. However, unless you are an
advanced user, you should not change some of these settings (such as the link speed, IP
settings, default gateway, and firewall settings).
This section contains the following topics:
• View IP settings
• Change IP settings
• Reset network settings

I would also just take a look under the wireless settings.

You may be able to just add the WPA password to connect.
But I would still reset the wireless first

Reset network settings
To reset the administrator password and network settings, press the (Wireless) button, and
then, using the buttons on the right, scroll to and select Wireless Settings, select Restore
Defaults, and then select Yes. A message appears stating that the network defaults have been
restored.