My mac would not boot so I formatted the drive and now it has no OS So there is a whole other backstory as to why my computer would not boot and why I needed to format the drive. The only thing I need to know is how can I install an OS to my computer. I tried CMD-R, but it only gives me the option to upgrade to Lion and when I click to do that it tells me that Lion is no longer available. I do not have access to other macs so I don't know how I can install an operating system on my own. Oh and my computer is one of the 2010 Macbook Pros.
When you formatted your drive, you must have been "standing" on some other boot drive ... backup (??). That said, clone its OS to your newly formatted drive. Use Carbon Copy Cloner ... the best. If you don't already have CCC, get it and install it on the drive where you "stood" to do your original formatting.