Most of the time when a printer used for a certain period the ink would dry out and caused an error message. What you do is to replace with a new inks pad inside the printer and reset that error message. Once it is done, your printer will work again!
For Printer Model: Canon i9100, i9950, S9000, i850, i860, i865,i550, i560, S400, S300, PIXMA iP3000:
1. Turn off printer
2. Hold down Resume button and press Power button.
3. Keep holding down Power button and let Resume button go.
4. Press Resume button 2 times then let BOTH buttons go.
5. Green lights will flash and then stop blinking.
6. When green lights are solid, press the Resume button 4 times.
7. Press the Power button and the printer should turn off, if not, press the Power button once more.
8. Your printer should respond as normal.
For printer model: Canon BJ F900, F890, F700, F500, S900, S820, S750 and S52:
1. Turn off the printer.
2. Press and hold the RESUME button, then press and hold the POWER button.
3. Release the RESUME button, then press and release the RESUME button two more times in succession. (you?re still holding the POWER button during this). The printer mechanics will move momentarily.
4. You are now in Service mode.
5. Pressing the RESUME key will select a function; for example, pressing RESUME 4 times will select the clear waste ink counter function. The lamp will alternate color with each key press.
1 times - Factory/Service test printout, including ink sensor check
2 times - EEPROM info printout
3 times - EEPROM initialization
4 times - Clear the waste-ink counter
5 times - Printer model setting. (more selections beyond this- leave this alone)
After selecting mode, press the POWER button to commit the change, and return to the top of the function selection menu. Pressing the POWER button again turns off the printer for a restart.
The procedures I am listing here may work for other Canon printers as well, but if you use them on Canon printers other than what is listed for each reset procedure, do so at your own risk!