Yahoo took away my old emails wih no warning-can I get them back?

Hi. I'm computer illiterate. When I discovered my old emails were gone I thought it was just my computer. Some of them are very meaningful to me. I did nothing to have them go away. If I would have had ANY warning I would have saved them somehow. Is there anyway to retrieve them? It"s been a few days. Please help me if you can. Tx, Marla