It sounds like you have lost the 'date' column. When you have the list of your emails displayed, there should be several columns of information, including (e.g.) the subject of each email, the name of the sender -- do you see all that? If so, at the top of each column there is a header, and at the far right hand end of that header bar there is an odd symbol with a small downward arrow. If you click on that it should reveal a drop-down list of all the columns that can be displayed. Make sure that 'date' is ticked.