Macbook Pro doesn't start

I got my Macbook Pro in January. It's been working fine recently until a few days ago when it froze and I restarted it. Since then it keeps loading but it doesn't start up. It just stays in the screen with the apple logo and the wheel spinning. A loading bar appears but it disappears before it even starts to load. I tried pressing Command-Option-P-R to reset the PRAM, but it didn't do anything. When I press Command+V or Command+S then /sbin/fsck -fy, it says:
Invalid sibling link
Invalid node structure
The volume Macintosh HD could not be repaired.

I have a lot of files on my MBP and after I lost power cause of Sandy, it's my only source to get my work done. There's no Apple stores I can get to due to Sandy and my work is really starting to pile up. Is there anything I can do to fix it?

The best I can suggest since you can't get to an Apple store to swap out that hard drive.... is to download "Disk Warrior" and hope that it can repair the drive. Here is the download LINK. However, you should know that this is an expensive program and can cost more than a new hard drive replacement. ($99.95)

I'm on my friend's macbook since mine doesn't start. Do I get Disk Warrior on this computer and connect it to mine? I don't know too much about this.

I'm just thinking here for a minute..... if you got your MBP in January of 2012 it should have came pre-installed with Lion. Did you try rebooting into your Recovery partition by pressing Command + R when restarting the machine?

If you can get into Recovery and have an internet connection, you can try reinstalling Lion by downloading it again from Apple. Let me know if you can get to the Recovery partition and we'll go from there.

I was able to reboot into Recovery and I do have an internet connection. It gives me the options to restore from Time Machine Backup (I haven't backed anything up), install a new copy of Lion, or repair/erase a disk using Disk Utility. So am I going with the reinstall Mac OS X option?

Sorry about getting back to you a bit late but got tied up with something else around here.

Go ahead and erase the disk first (since you have no backup anyway) with Disk Utility. Then format it as Mac OS Extended Journaled. At the same time, name the hard drive "MacIntosh HD". After doing all of that, download and reinstall Lion from the Mac App store with your internet connection. It's going to take a while to download so be prepared for that.

Let's hope the erasing of the hard drive and reinstallation will repair the invalid sibling link and invalid node error. If it doesn't, it might be best to just change out the hard drive for a new one rather than spend the $100 for Disk Warrior.