Vanishing E-mail?

I recently had an occurrence of vanishing e-mails --specifically 14 months of e-mails from mid-December 2007 to September of 2006 just up and disappeared out of my in-box. E-mails that pre-date that date are still intact and some date to 2002. (Yes, I know I'm a pack-rat and save everything.) I called the internet provider company and their tech was mystified and told me to call microsoft. Microsoft told me they could help me retrieve the information but I had to give them my credit card number and $59. The information I had pulled into separate files are intact but stuff I didn't get to or create folders for is gone.

Any ideas on how I can pry it loose from where ever it's hiding?

Thanks in advance.

If you remember a few keywords on the lost items you might try the search option in the start menu.
Just type in a couple of significant keywords in the all files and folders window. It might find some for you.