Installed Windows in wrong partition and now shows "no bootable device" I chose the wrong partition to install Windows on my MacBook Pro Retina.

How do I reinstall Mountain Lion? I tried ⌘R but the only thing I get is:


  No Bootable Device -- Insert boot disk and press any key
Since Boot Camp sets your Windows partition as the Startup Disk, some keyboard commands on boot become very temperamental or may not work at all.

Try holding ⌥ alt on startup - see if you can select the recovery partition.

If not, you might have to re-install the OS from disc or external drive.