Help! MacBook pro doesn't boot past gray screen spinning wheel

Hi,
My MacBook pro was in chrome on youtube and froze. No reaction to anything not even mouse coursor. I did a hard turn off thinking it was stuck.
Now it is stuck:
When pushing the power button it goes to gray screen, apple sign and spinning wheel. Than just black screen. Ventilator sounds but nothing on the screen.
I've tried cmd R boot - same result. No change when tried cmd + power. Same with cmd control r p. nothing.
What can I do?
I've got an external book hard drive with time machine. But the MacBook won't start up...
Help! Please
Liz

blueroom said:

How old is the MBP? Could be an HDD failure.

Click to expand...

It's about a year and a half old. Had Lion Os x. Never fell down or had liquids spilled on it. Never did any problems till now...

blueroom said:

How old is the MBP? Could be an HDD failure.

Click to expand...

GGJstudios said:

This may help, if you haven't seen them already:

Mac OS X: Gray screen appears during startup
Troubleshooting: My computer won't turn on
Mac doesn't boot​

A flashing question mark appears when you start your Mac
OS X Mountain Lion: If a flashing question mark appears
Mac OS X 10.6: If a flashing question mark appears

Click to expand...

Tried the links but in vain - start sound than apple gray screen and spinning wheel. Than black screen. Strangely the keyboard backlight is on and other lights work correctly. When this black screen is there pressing cmd and other keys produces an unhappy sound but no visual reaction