Why can't i seem to resolve this /efs problem?

[AC Question]

I have a Samsung galaxy tab 2.One day as I decided to wipe everything,i noticed a message in the recovery mode saying unable to mount efs.I cant open my tablet or anything.After looking on the internet,people were telling me to flash a custom recovery like CWM.In order to do that I need to root my tablet.To root my tablet I need to enable USB debugging,which I can't because I can't access it.Can you help me please?