My extensions folder is completely empty in My MacBook Pro 10.6.8. How do I reinstall?

MacBook Pro 10.6.8. (7,1) My extensions folder is completely empty. How do I reinstall? Need to eliminate Extensions/Apple USBEthernetHost.kext within it even though it does not appear in that folder.Could be the problem why my Canon printer is not working? (Rollers not grabing the paper) Keep getting the message,"System extension System/Library/Extensions/AppleUSBEthernetHost.kext was installed improperly and cannot be used. Please try reinstalling it, or contact the product's vendor for an update." I also got this message after doing a small upgrade to system 10.6.8 but at the time paid no attention to it. These are all the stats I can give.