when I turned my ipad on, all my email disappeared

In most cases, this happens when a computer user has a desktop or laptop in addition to, say, an iPad. If the settings aren't correct, you can "lose" email. It can happen if the ISP changes their settings, or if a user has incorrectly input their settings.

Based on the information you provided, you only have an iPad. In that case, I suggest you double-check the settings, especially at it elates to the ISP.

The messages appear and disappear because your computer downloads emails, then deletes them because the settings are incorrect. I've seen this happen on two of my machines, and fixing the configuration resolves it immediately. You can fix the settings on your iPad by going to Settings/Mail/Account. Make sure you have your settings and passwords handy, and correct. "Add Account," and choose "Other." Add the "Mail Account" and "Server Account." If you have any question what these are, you should contact Earthlink for the configuration info. Configuring your iPad might take take some trial and error, so exercise patience.

Just so you know... If you really need a "lost" email message, you can always use Earthlink's web-based email feature on your PC.