File is listed, but won't let me open it?

I created a Word document in Word 2010 on Windows 7 vista on May 7th, 2012 and put a password on it. the computer says the last time I modified the document was may 16th. Today, I tried to open the document, and it says the file could not be found. It also says that the file is 49kb, and I know I wrote hefty paragraphs in that file, so there's no way that's a valid size. I don't recall deleting this file, as it is a very important file with precious information, but there is a possibility that I might have. But if that's the case, then why is it still listed in my folder? How is it that this file got deleted if I didn't delete it? Has it been deleted at all? Is there any way this file could be recovered?

I've already done a full system search...nothing related to the file is openable, though.

Any helpful information would be greatly appreciated.