How can I retrieve messages I have erased by...

Question

We had five messages from our grandsons we couldn't bear to delete - we would either listen to them (they were hysterical) or skip by them. Today I hit erase five times instead. Is there any way that I can retrieve them? Is there a code or something?I have an older model Sony phone / ansering machine Digital 900mhz sppA973. I erased a message today that was from my Dad - he passed away 3 -1/2 years ago and I sometimes like to listen to it. PLEASE HELP!!!