I've got a Macbook Pro late 2011 which has been (and still is/was) great. I was running High Sierra and decided to do a reformat and reinstall from USB. However, something went wrong and it hanged on the last part of the install.
I rebooted and used the recovery option but I guess I'd managed to wipe something as it now only gives me the option to install Lion (which I think it shipped with). I've gone ahead and done this but cannot now upgrade to anything later. I think I need to upgrade to Mountain Lion first but cannot find this in the app store. The only OS I find in purchased is El Capitan and trying to install this doesn't work.
Sorry for the rambling post but any help would be much appreciated I'd be really sad to lose this it's been such a great workhorse for last (nearly) 10 years!