Please help me out, Macbook pro won't start up and I get a grey circle crossed with a line..

Today, I started up my macbook which was sleeping all night, and fully functional the day before.

It forced a restart, after which it would not load start up at all. It first displays the grey apple logo followed by the circle with a line slashing through it, similar to stop sign.

I looked up some solutions on my mobile.

I tried resetting the p/v/n RAM ?? (not sure what this is), safe booting ( it did not work just a white screen), and pressing cmd+R to get to the disk utility menu.

In the disk utility menu, most of the time it just crashes whenever I click repair, verify, or anything. The few times it didn't crash, it gave me an error message saying something along the lines "some files where not found".

I followed a guide, partitioned my hard disk, and installed OS on it and I am now using my mac with my hard disk plugged in to be able to use the OS.

Needless to say, it is very slow, inconvenient, and mod importantly all my data is missing.

I'm not even sure what's wrong, or what my situation with the hard disk is, so any help is appreciated.

Also I don't know of any apple stores in my city, the nearest one is a 3 hours drive.

Thanks in advance for any input.

I have a 15 inch Macbook pro with retina display (2013 edition if i'm not mistaken), with OS X Mavericks 10.9.5