Hi
I created a bitcoin wallet once to pay for a service from a site, but i never bought the service and kept the bitcoins. I also very shortly did some mining.
And i changed OS a few times since so i have no files what so ever form then.
So if i don't have a wallet.dat file i have lost that wallet for good ?
//Brian
Sorry to say but given your story the Bitcoin are most likely gone forever.
To be sure please explain exactly what you mean when you say "I created a bitcoin wallet" - be very specific with as much detail as possible.