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

So, I’ve had my MyBook for several years and it’s been a great backup tool. As such, I’ve got a lot of very valuable data on it. I was plugging it into my computer as normal today, unlocked the drive, but found that it simply wasn’t showing up in the WDSmartWare menu. I went to My Computer. It didn’t appear to be there. And then I got the error message, “You need to format the disk in drive I: before you can use it.”
I really hope this doesn’t mean I’m going to lose the files on there. I’ve looked around online but haven’t found anything much that was of any help. Maybe someone here will have an answer? I’ll be glad to provide anything I need to!

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.