How do I reset my MacBook Pro to factory settings without the original install disc?
'Factory reset' can be done with Apple's Internet Recovery by holding  Cmd ⌘     R   at the boot chimes.

Check your machine is capable of this or whether it requires a firmware update to do it before actually trying it, or you may end up with an unusable machine &amp; then have to get hold of OS Install disks.

You may also  want to go to Disk Utility &amp; do a secure erase first, just to lessen the chances of someone trying to recover your old data [unlikely but possible on a simple wipe &amp; install]