The answer to your question "why my Canon printer won't print?" is very simple. There are different reasons that result in this error:
Network problem or poor network
Interference from Antivirus or Firewall
Corrupt/Incompatible Router Firmware
Corrupt Installation of the Printer Driver
Hardware problem
There are many more errors that result in a Canon printer won't print error. Knowing the right cause can help you deal with the problem and make it work again properly.