Remember all your actions with a mailbox and letters, which you made yesterday. Most email services have a special button called "Clear Inbox". When you click on it, you might accidentally delete all existing e-mails. In this case, pay attention to the folder "Trash" or "Deleted". After removing all of the information initially goes there and stays a while before the automatic cleaning packs server. If your letters really were in the Cart, reset it by pressing the appropriate key.
Inspect the folder "Spam" or "Junk mail". A large part of the mailbox has automatic protection against suspicious messages and automatically puts some of them in the appropriate folder. Very often it turns out even those Inbox that are not spam and important to the recipient. Restore them in the main folder and mark it as important in order to avoid destruction of the robot.
Search for emails in your Inbox, if the folder is filled with them, but you don't see what you need. Perhaps you accidentally chose a different way of organizing information, in which new letters lost among the old. Search for the name of the letter sender or contained in the attachment phrases will help to detect the loss.
Make sure that your email has not gotten people. If you notice a suspicious missing your emails, or they are read without your participation, the mailbox may be hacked. Change the access password to be more complex.
Refer to the administration of the postal service. In the preferences window or help, you can find the coordinates for communication with technical support. Write a letter to the specified email address or call us, outlining the problem. If the cause of the disappearance of the letters was technical problems of the postal service, the administration will help you to solve the problem quickly.