Your printer likely still has retained the settings that you gave it to connect to your "old" router.
The printer is lost, and will not be able to find its way to your new router until you reset the printer back to its new, out of box settings....and then configure again to work with your new router.
For specific details, consult the documentation that came with your printer, or log into the online support site for your printer.
Sometimes, something as simple as powering off the entire network and then powering it back up...starting with the modem first....will fix a problem like this.
Maybe if you could provide the make and model number of your printer, another user who has the same model might be able to offer some tips on how they got things working.