Flashing folder with a question mark on start-up

My Problem

One day my MacBook just hangs. Completely. After rebooting all i've got was a flashing folder with a question mark. Disk Utility couldn't find a hard drive in my system but i could clearly hear it spins.

My Fix

The repairing process was fast and straightforward. 10 screws on the back, two on the inside, bend the new HDD cable a little, replace the old non-working one, get all parts back together.

My Advice

The symptoms like this not always mean "your HDD just got broken, you've lost all your data". Try not to panic :)