Whn you say you saved your draft, where and how did you save it?
The site usually saves stuff drafted in the reply box, even if you hit the red x button (I just tried that now). I think if you just have a wifi hiccough at an inopportune time or if the server does the same it might miss something, but it isn't an issue I have regularly encountered.
I must say, if I'm doing a longer response, I usually draft it in word, then C&P over.
Ah. If it was a new topic, then the same thing has happened to me. I have always just assumed that if a new thread is closed down without being published, then it is deleted without a draft version available.
The drafts in the reply box only seem to save when they are on a pre-existing thread.