1. How can I prevent email going to the trash box without having seen it?
2. How can I move that mail back into the inbox?
1. In order to prevent it, we need to find out what is causing it. Do you have any filters/blocked senders? Is your Spam Detector set to move spam to the trash? Are you using any POP3 clients to check your mail?
2. You should be able to check the box next to any messages you want to move, then drop down the "Move To" menu and select "Inbox" from that list.