To troubleshoot your printer’s sudden language switch, there are a few steps you should take in order:

1. Check the printer’s language setting.
   Print a Settings page to verify that the language specified is the correct one.
2. Verify all the cables are securely installed and connected. Try reconnecting the cables if necessary.
3. Make sure the printer driver software is installed and configured for the language you need.
4. Check the printer’s input tray. Make sure it is stocked with the correct type of paper and language.
5. Clean and unclog any jammed paper.
6. Perform a cold reset on the printer, which resets all settings to their factory defaults.
7. Reinstall the driver, or download the latest version.