Got an Apple, Mac, or iOS tech question? We've got the answer. This time in Ask, we'll tell you how to install Mac OS X on a brand-new hard drive, even if you don't have a functioning installation DVD (or an internet connection).
I’m trying to install Yosemite on a MacBook Pro with a new, blank hard drive (the old one died and was replaced). I have a copy of Mountain Lion on a DVD, but I don’t seem to be able to install it. And if I go to Apple’s website on my Windows PC, there’s no Yosemite download button. Am I marooned without an OS?
If you have a newer MacBook Pro (or any Mac, for that matter), you can start the computer in Recovery Mode by holding down Command + R while it's booting up. Even if the startup drive isn't available, you should still be able to enter recovery mode, select a Wi-Fi network, and perform an OS X recovery via the internet.
If you have a newer Mac, the easy solution is to use Recovery Mode and reinstall OS X online.
If you're using an older Mac, however, you'll have to try some other tactics. Don't worry that you can't see the Yosemite download button on your PC; it won't appear unless you’re viewing Apple's site on a Mac, and you need to get your Mac to run at least Snow Leopard in order to be able to download the Yosemite upgrade.
Apple’s website is smart enough to only give you the upgrade option when viewed from Mac.
Since your Mountain Lion install DVD isn’t working, you have two options: if you know someone else with at least Lion installed, you could use DiskMaker X (diskmakerx.com) on their Mac to create a bootable install disk; alternatively, you can call Apple customer support (1-800-275-2273) and give them the serial number of your MacBook. If you ask them ever so politely, they should agree to send you a DVD for whatever version of OS X was originally installed on your MacBook. You can then use that to bootstrap yourself back up to Mavericks.