C'mon dude don't let em get you down! Happens to a lot of us, just dishonest people, eventually they get caught and booted. You've got 100% rating I see and many sales, plus you have crazy cool stuff!!! :)
Yeah, I've been there too. If I ship an item without tracking, I make sure to get an itemized receipt with the buyer's zip code as well as take pictures of the package with their address on it. Tracking is not the only way to prove you sent an item! I know this for a fact as I have won several disputes that way. Also, Stamps.com is really awesome for keeping a record of every item you purchase postage for. You can even email the info directly from the site. Just a few words of encouragement. Many blessings!