Please follow the instruction to set the language back to English.

1. Press "Return" button 4 times, the printer screen will show as below.

2. Press "Menu" button.

3. Press "▼" 3 times, and "OK" button.

4. Press  "▼" 1 time, and "OK" button.

5. Press  "▼" 1 time, the screen will show "English", then press "OK".

The system language will be changed to English.

If you need more information, please see attached file: M6600NW How to set the language back to Enlish.pdf