lao che,
Unfortunately, this happens occasionally to people who use forums: they type up a long post, then somehow the server goes down or they get automatically logged out (from "inactivity"), and they lose their entire typed-up post.
The best thing I can recommend is to make sure you at least copy the text to your computer's clipboard so that you can re-paste it into the box should it somehow get lost. If you want to be even safer, you can copy and paste it into notepad or some other text editor to be absolutely sure you still have it in case the text disappears.
Sorry about the hassle!
- Franco