Windows 7 won't back up.

[dinamike]

hello i tried to back up my windows 7 but it countinued for like 6 hours,so i stopped the the back up process then after a while i tried to back up it agian but it won't back up .please some one help

 

[Mark56]

What is the size of the drive/partition that you are trying to back up and what are you backing it up to?