Platy lifespan

Does anyone know how long a female blacktail Platy will live? I got my
fish a little over 2 years ago and she's been very healthy and
productive over the years. She was an adult when I bought her (at a fish
store). Today I got up and she was upside down and an hour later she was
dead. I was just wondering about how long these little fish live. I've
had my tank about 2 1/2 years and have had very little problem with
fish. I'm hoping that there's not bigger trouble brewing in the tank.
All other fish look healthy. Thanks for any insight...