There’s no administrator account on my Mac!

I’ve bought a second-hand iMac through a friend of a friend. Naturally, the Mac came completely reset (it is running Mavericks) but the only user account on there seems to be an ordinary account, not one with administrator access. How can I add an admin account without having admin privileges? Will I have to reinstall everything from scratch? I don’t have the OS X discs! Jeremy Linton There aren’t any OS X discs anymore. If you need to reinstall, you’ll do it using the recovery partition and the App Store. But you don’t need either to fix this. Restart your iMac with ç+s held down. This puts the Mac into ‘single-user mode’ which gives you full access to the filing system. Now mount the drive by typing at the command prompt. Next you need to trick OS X into showing you the Setup Assistant again, which you do by making it think that the OS hasn’t completed its original install. The command

deletes the file that OS X uses as a marker for this. When you restart your Mac, you’ll arrive at the welcome screen that you normally only see on a new Mac or a fresh install. This enables you to create a new admin user account (you must make sure it is a new user account name, not one that already exists). You can use this admin account to change or create any others as you wish.