Windows 7: unable to delete folder and can't read from source file or disk

hello. i am facing two kindsa problem with my ext hard disk!

1. there's a folder in my seagate 1tb goflex external hard disk, which am unable to delete. wen i checked the properties it showed that the space occupied by the folder is 1.5PB!!!! its ridiculous n strange at the same time! if i try to open the folder it says "you need to format disk before you can use it".

2. every time i try to copy some files onto/from my hard disk it says "can't read from source file or disk". i have some valuable data worth 700GB on my hard disk and am unable to transfer em onto any other device so i can format my hard disk. somebody,anybody please help me out. thanks!

You might want to give Unlocker a try. It deleted a folder I was unable to delete any other way on my Win 7 Pro X64 system.

If you have Win 7 X64 then you will need the 64bit version of Unlocker.

Have you scanned your machine and external drive for malware?

Do you have access to a Live Linux CD (e.g. Ubuntu, etc.)?
Linux doesn't care about Windows permissions and it can read multiple types of HDD formatting.