When I turn on my printer it's the light that says alarm flashes and the screen says check printer. Please someone help me.

Oh yeah my printer is a : canon pixma ip621od

Also I looked in the manual and it said to turn it off and then on but that still didn't work.

Suggest you might try un-installing the printer through the Control Panel/Printer. Then unplug the printer from the computer. Shut down computer. Wait a couple of minuter. Restart the computer 'without' the printer being plugged in. Let computer fully reboot, then shut down. Again, wait a couple of minutes. Plug the printer back into the computer and restart. Your PnP feature should detect the printer. You may be asked for the manufacturer CD to reinstall the drivers or select it from the drop-down list. If you do not have the CD, the drivers are available from the Canon web site.