Generally when content is missing it is often related to caching plugins. One of those plugins is OptimizePress which can sometimes conflict and make it seem the content is missing.
Here is what you can try:
- Deactivate all plugins and check again.
- Ensure the server has no caching enabled by asking your hosting
provider. - Check to see if your font is not the same color as your background.
If all of that fails, you can ask your hosting provider to see if they have a backup of your site to restore your pages.