There are a few things that you can do in order to try and fix the canon printer offline issue. First, you can try restarting both the printer and the computer. Sometimes, this can help clear up any communication issues that may be causing the problem. If this does not work, you can try unplugging the printer for a few minutes and then plugging it back in. This can sometimes reset the printer and help it to communicate with the computer properly. If neither of these solutions work, you can contact Canon customer support for further assistance.