removing and adding a printer

Safe Boot from the HD, (holding Shift key down at bootup), does the problem occur in Safe Mode?

Safe mode attempts to repair Disks & clears lots of caches, so if Safe Mode works try again in regular boot.

Any devices that previously appeared in your Printer List and Fax List will need to be added again after resetting the printing system.

Resetting the printing system in Mac OS X...

1. To use the Reset Printing System feature in Mac OS X, follow these steps:

2. Choose System Preferences from the Apple menu.

3. Choose Print & Fax from the View menu.

4. Control-click on list of printers on the left side of the window, then choose "Reset printing system" from the contextual menu. If you don't see a list of printers, Control-click on the text "Click + to add a printer or fax" and select "Reset printing system..." 
   
  As an alternative, if you currently have one or more printers listed, you can Option-click the "-" (Remove printer) button.

http://support.apple.com/kb/ht1341

Reboot.

Know the basic reason for why the printer is not responding!! reinstall the printer driver can help alot but follow more steps to access my Canon printer over wifi or How to Fix My Canon Printer Offline Issue

Follow the following step for the solution of it-

Solution 1: Restarting the printer spooler

Solution 2: Disabling Use printer offline feature

Solution 3: Reinstalling software of Canon printer

Solution 4: Solving connection issue

Maybe this can follow the problem if not then you can go through the referred link i have been through

And If Canon wireless printer not responding

Solution No. 1- Switch on Network Discovery

Solution No. 2- Restarting the printer spooler

Solution No. 3- Disabling third-party firewall

Solution No. 4- Using of printer troubleshooter

Thanks

Good work Hans. :)