Be sure to power off the printer, wait a minute, and then power it back on (there is a switch by where the power cord is located on the back of the printer) and then wait for it to display “ready” at the LCD panel. My experience is that just using the power button in front doesn’t solve the problem in this kind of case.
Sometimes after doing the above, the printer is still non-responsive. In that case I’ll reboot the computer. That solves it 99% of the time.
Check that the IP address of the printer is what you expect it to be. With mine, the IP address is on the front LCD panel. Once you see it, ping that address. If the printer is on it should respond.
An alternative to above is to open a web browser and put in the address of the printer. In my case it’s on http://10.0.0.253
but in your case it will almost certainly be different.
If for some reason it doesn’t respond to any of the above, check that the network cable is connected properly. Remove and then re-seat the cable on both ends and listen for the click as the cable seats into the socket. Re-test after that. If it still doesn’t respond, try replacing the network cable.