POOF! Gone! Just like that. What happened?????

Tonight I wrote a long D-mail to someone I correspond with a lot. I was still writing when--I must have hit some key, accidentally, with my left hand, and the whole D-mail was GONE! However, as I did not realize it right away and continued typing, whatever i was still typing was seen on a new, blank D-mail screen.

This has happened to me maybe twice before. It is so frustrating! There is NO way I can re-type everything i was typing. How can something just disappear?????

I typed up a new, shorter version, explained it all and hit "send". Then I typed a bunch of "Jibberish" in a new screen and hit every key the left hand would hit (accidentally) to see if I could make my typed "message" go away. NOPE!

Can anyone tell me WHAT it is that I may have hit (accidentally) on the left bottom of the keyboard to make a whole typed D-mail disappear???? NO! It was not sent. I checked it. It was simply GONE! On the left all there is is the "caps lock"--"shift"---"alt"---"ctrl"--- and the windows key. If I had hit any two of them simultaneously, unintentionally, would that have caused all my text to be deleted? Which ones????

Please help!!!! Gita