First, make sure the printer is still connected to the wireless network. You can do this by printing a wireless network test. Press the wireless button on the front of the printer. Press settings. Scroll down to and touch Run Wireless Test. Once the test is done, a page will print. This page will let you know if the printer is still connected to the network or not.
If it's not connected, run the wireless setup wizard to reconnect it.
If it shows connected, the next thing to try is a power cycle of the network. Turn off the printer, Mac, and unplug your router. Wait 30 seconds. Plug in the router, but leave the printer and Mac turned off. Wait for 1 or 2 minutes to give the router a chance to stabilize. Once it's stable, turn on the Mac and printer. See if it will connect now.
If it still won't connect, try the steps in the document below.
Printer Does Not Maintain Wireless Connection
Let me know what happens.
I am a printer tech for HP.