I spent about an hour working on making something in the homebrew creation, and when I went to upload a picture it said the file was too large. No big deal. I went back to the page to try and change the picture, everything I wrote was gone. Just not even there anymore. This is a massive oversight on the part of whoever made this. If the error message popped up in a new window or tab, I wouldn't have lost an hour of progress making something. I wouldn't have to restart. I wouldn't have to be posting this. No. Because I wanted to use a png instead of a jpg everything is gone, and I'm upset.

Always save after changing something. There is no auto-save in homebrew. If you add a modifier or image without saving, you will lose changes.