Error checking external 1TB hard drive within Windows 7 taking forever

Hi,

I have been having some issues with an external 1TB Seagate hard drive of late, so I decided to dismount the drive and run check disk within Windows 7 (Computer>Right clicked on F: drive>Properties>Tools>Error-checking>Check now>Checked 'Automatically fix file system errors' and 'Scan for and attempt recovery of bad sectors'). Check disk has now been running for over 24 hours, and has been stuck on '273666 files processed' for at least 4 hours. I have a lot of important files on this drive which I can't afford to lose. I backed up the drive a few days ago, but some of the files failed to backup correctly, which is the main reason I decided to check the disk.

I tried opening an important Photoshop file (which is one of the files that failed to backup) and received a 'Could not complete your request because of a disk error' error message. I really need to restore this file if possible, as hundreds of hours of work have gone into it, and starting from scratch is something I don't even want to think about. Should I wait it out even longer, in the hope that check disk completes, or should I click 'Cancel' and try again? If I cancel, will it have to start from scratch if I decide to check the disk again, or will it continue from where it left off? I welcome any other suggestions.

Thanks in advance

Windows explorer crashed and restarted before check disk finished. Luckily, I can now open the Photoshop file in question, which I have backed up to another external drive. I will try to run check disk again, but in the meantime I will buy a new external drive.