OK, I am getting a little confused now...the computer is at a friends or the flash drive?
If the flash drive with 10.8 installer, and you cannot get it back, then the alternaives are to try an internet recovery or buy Snow Leopard from the Apple on-line store for $20, install that, software update to 10.6.8 (what comes ins 10.6.3) and then download Mountain Lion or Mavericks. I would not buy any ML installer flash drive off the internet since Apple has never offered that and the installer would then be suspect.
A 2009 should accept the retail version of Snow Leopard if it will not accept the internet recovery.