It happen to me in the past where I lost a wall of text since I didn't click preview and then I accidentally close the page or reload. But, after that, whenever I want to create a long post, I edit on notepad first, then I copy the text and post in this forum.
I did this most of the time too; after I experienced one painful experience, which was when I was typing and making comments on the forum on a particular thread, I got carried away and left to attend to it. When I tried to come back to the forum, I noticed everything had been wiped out. Notepad is a lifesaver in such a case. Sometimes I wonder if it's the network or low memory that usually leads to that reload.