Go to listings > Saved listings > then find the link to the right that says 'html,' Click that and a box will pop up with the html. You can copy that and paste it to notepad or wordpad and save it on your computer.
I don't know what server disaster would cause you to lose everything beacuse it would still be in your closed listings on Ebay for a while
(60 days ?).
I hope this helps!! Good luck!!