May have deleted OS system files, Mac won't boot now...

I was trying to help my brother clean up his hard drive (he had all sorts of weird downloaded games, other software, multiple iPhoto libraries, etc), and I saw some folders and files I had never seen in my ten years of owning Macs. I figured they were weird downloads, and he didn't know what they were, so I deleted them. They weren't in the System, Library, or any other folder like that, they were just sitting out in the open on his hard drive. I also got rid of his Boot Camp partition because nothing was on it and he wasn't using it. (I did this through Boot Camp Assistant, so that shouldn't have caused any problems).

Now his MacBook doesn't boot. It sits on the gray screen with the apple logo and the gray spinning circle. I've tried a safe boot (no luck), resetting the NVRAM/PRAM (no luck), and tomorrow we'll try booting from the Install disk and doing a disc repair. I guess the next step after that (following Apple's support link Mac OS X: Gray screen appears during startup) is to do an Archive and Install, which if I understand correctly, will do a fresh install of the OS without wiping out his files.

A couple questions:
1) Does anyone know what to do if you accidentally delete crucial system files?
2) What are my options? He has ignored my advice over the years to back up his data, and he has some invaluable info on this hard disk (his children's photos and videos).

I'm pretty desperate... any advice?

Shouldn't be a big deal if you have the install disc. Double click the Install OS X icon, then select the destination disk. Select “Archive and Install,” and then select “Preserve Users and Network Settings".

Everything should still be there when you are done.

Friends don't let friends not back up!!

brairden said:

...Friends don't let friends not back up!!

Click to expand...

That should be siged. >_<"

Thanks for the replies...

I just realized something crucial. His files were extremely unorganized, and his iPhoto libraries (don't know why he had more than one) were NOT in his Home folder. Most things were not in his Home folder. They were either in his shared folder or in his "Macintosh Hard Drive" folder. There were also lots of things on his desktop.

I've read about the files that are saved when doing an "Archive and Install", and it looks like these files are not part of them.

Am I screwed? Any thoughts or advice... please send it my way!

I am not 100% sure on that. Why not pull the drive out and pop it into an external enclosure? You could then back up the files to another mac before reinstalling the OS.

same problem.

brairden said:

Shouldn't be a big deal if you have the install disc. Double click the Install OS X icon, then select the destination disk. Select “Archive and Install,” and then select “Preserve Users and Network Settings".

Everything should still be there when you are done.

Friends don't let friends not back up!!

Click to expand...

This is the exact problem I just encountered... accidentally deleted something... almost the same way... just cleaning up iphone library...

But I am not getting this option to "preserve users and network settings"
Upon booting the disc.
I choose english, then continue to instal drive and the harddrive is there... my harddrive with all my stuff, but when i double click on it, all it gives me is replace and it says all my data will be erased....

Is there any other option.

brairden said:

I am not 100% sure on that. Why not pull the drive out and pop it into an external enclosure? You could then back up the files to another mac before reinstalling the OS.

Click to expand...

Would this work... I'm a little mac illiterate. would I have to take this to a mac dealer to preform this?