An error ocurred on your 2,000$ Mac computer. If you want to recover your lost data, please bring this computer to your nearest Apple Official Repair © center just for 400$.
However, if you don't want to, you can of course reset this computer from zero, but you will need a new Mac OS X 'insert random spanish name' license starting from
Keep in mind you are still in the website so if you are fullscreen or your neurons are that limited to don't notice it, don't worry, your PC won't explode right now.