rembertoguido
Hi,
It's weird, normally, creating a new page should not affect other page.
You can check the Revisions of that page and select the suitable one. For example: JA Builder > Edit homepage > Settings > Revisions: http://prntscr.com/ogmu4j
The best routine when creating pages via JA Builder is that after completing a page, you can backup that page by exporting it to a file.