Have I got a good one!
I can't tell you how many times this has happened to me! If you like to make your new listings by using another as a template; using the "sell similar" link, this may have happened to you. You're in the middle of filling out a listing by making changes to the one you're using as a guide (usually almost done) and you make a spelling error or want to make a change so you highlight and click backspace. What should happen is the highlighted items should delete or go away. Things don't always go as planned on ebay however, occasionally when I do this, it sends the whole page BACK! So you click the forward button to get back to the page you were on and do you know what happens? EVERYTHING you typed in including any photo's you uploaded are gone! You're back to exactly where you started and you just wasted probably 5-10 minutes of your life thanks to ebay!
I used to get infuriated at that!
What I learned is when that happens, go to your "my ebay" section and click "drafts". It should be there with all the stuff you changed including pics. (you may see some others you thought were lost there too!)
Another related item; sometimes you start to make a listing but decide to hold off. Ebay is screwed up (big news flash there huh?) and usually says that you saved the number of allowed templates so you can't do that. Don't fret, just close the page or go on to another as you like and when you want to continue that listing, go the that drafts section in my ebay and it will be there waiting for you to complete it.