What if?? [something bad happened to my mac]

I think you hold command-r on booting it up. Have you had a power cut? If you have, unplug your power cable for 1 minute, when up it back in and boot up.

 

This is why it's prudent to create your own bootable Mavericks installer, just if something goes bust.

It's easy.

Download Mavericks from the App Store, but quit the installer app it opens. Then, use DiskMakerX to create a bootable installer out of it on a pen drive.

 

Or use the inbuilt Apple way....

Create Mavericks USB Installer

 

Not necessary

Although the suggestions of the previous posts are wise to follow, they aren't necessary. If you can get your Mac on the internet, you can alway reinstall the OS like that. Holding cmd+r during boot will put you in recovery mode. Most of the time you can use the recovery partition that is on the machine to reinstall without the internet, but if the recovery partition isn't there for whatever reason, you can connect to the internet and reinstall the OS for apple's servers.
Also, when was your last pc purchase? For years windows computers haven't come with discs either, but instead restore partitions way less reliable.

You can also get an external disk and use time machine, super duper or other backup software(or the do it yourself way with either terminal or disk utility), to make a bootable image on the disk, that you can install or run from in case of emergencies.

 

I didn't receive reinstall software discs for an HP laptop I bought new in 2001 or 03 and it came with a partition that you can boot from to reinstall everything back to a brand new state, the MacBooks are very similar.
Like someone mentioned hold down CMD+R for recovery, as long as you have internet, the version of OS X that shipped with your Mac will load.
Personally, I would purchase an inexpensive 8GB USB drive, Google search How To create an OS X USB Drive.
(or look to DiskMaker X)
For the 1st year if it doesn't boot whatsoever, take it to, call, send to Apple.
If you want that option for another 2 years then purchase AppleCare.