"You need to format the disk before you can use it" error?

[Ichigo]

Hi, since you are getting the message to format, it is possible that some of your files are corrupted. You should be able to recover most of them using a data recovery program, you can find several options using Google. If that fails you can also contact any of the data recovery partners on the support page. 

http://support.wdc.com/recovery/index.asp?wdc_lang=en