I suspect from all that you have described, that the printer's IP address has changed.
Was the router restartd at some time, *before* the problem happened? if so, that makes it more likely.
Try printing off a Network Configuration Page (to show the printer's IP address as currently set), or otherwise get its currently set IP Address.
And on your computer, go to
and then enter this
and press the RETURN or the ENTER key, once. That should produce results showing the
IP Address information, which has to relate to the printer's IP Address, in order for it to be usable. (That will also show the computer's IP address, which might be significant, so note it also, please.)