My iPhone no longer recognizes my printer.

Use AirPrint to print from your iPhone, iPad, or iPod touch

Learn how to print from your iPhone, iPad, or iPod touch to an AirPrint-enabled printer.

Before you begin

• Confirm that your printer supports AirPrint. Contact your printer's manufacturer for details.
• Make sure that your iPhone, iPad, or iPod touch and your printer are connected to the same Wi-Fi network and that you're within range.

Hi,

In case of difficulties with AirPrint, and if the setup is OK, you can try the following procedure (in the exact order):

Power off the Wi-Fi router, the printer, the iPhone, and all other devices/computers. Wait two to three minutes. Power on the router. Wait two to three minutes. Power on the printer. Wait a minute or two. Power on the iPhone. Finally, power on all other devices/computers.

About AirPrint - Apple Support