mac wouldn't boot, flashing folder icon, keychain disappeared

[Patrick-32]

MBP LATE 2011
EL CAPITAN

Out of nowhere last night my mac shut down and would not start, it kept flashing an icon like a folder, and then showing able logo and restarting, no idea how it happened, it took me 6hrs before it started working, but since i logged in all my keychain has disappeared.

When the laptop was restarting and going back to fashion icon folder at start up, at one stage it came up with code. Never seen it before, had not time to take a photo. it reminded me of windows BSOD error, but this was in top left.

Im concerned about who all my login details have disappeared. the laptop works now but i'd really like to know what happened.

Laptop worked perfectly until last night when this happened.
[doublepost=1458296570][/doublepost]here was what i was seeing

 

[maflynn]

Looks like the computer is unable to find a bootable volume. Can you try rebooting into the recovery partition (cmd-r)?

 

[Patrick-32]

Looks like the computer is unable to find a bootable volume. Can you try rebooting into the recovery partition (cmd-r)?

Yes thats working, Can i fix it?

 

[maflynn]

Check the drive for errors by running Disk Utility, if it comes up clean try re-installing OS X.

If you have access to your data on the drive, I'd look to somehow back it up before doing anything else.

 

[Patrick-32]

I am u

Check the drive for errors by running Disk Utility, if it comes up clean try re-installing OS X.

If you have access to your data on the drive, I'd look to somehow back it up before doing anything else.

I did a disk first aid. My hard drive is an SSD about 6months old. I have taken out the optical drive and used a caddy so the disk drive is now where optical drove was and i run the OS from the SSD.

Is there a way of reinstalling the oS while keeping programs and files?
Is there a way to find the keychain login or are they gone now?

I have it backed up with time machine it think, is there a way to get the passwords back instead of the whole thing?