yes i used WalletGenerator.net, exactly as you described : wipe the computer, and go online again afterwards
no i dont have, it was a single one
Do you access WalletGenerator.net on your browser / do you download it from GitHub and run it offline?
If you access the website, then most likely it's the cause your Bitcoin was stolen.
but why its still unspent?
do you think its possible to write to every single crypto market to report this adress ?will it work out?
There are few website for it such as
https://www.bitcoinabuse.com/, but i doubt you will get your bitcoin back. At most, the thief can't sell/use Bitcoin on exchange/service which follow regulation.