I can't mount my hard drive, and my login is gone

I have two major problems: I need to find a way to mount my hard drive, and if possible, restore my non-admin login account to my MacBook.

My 2010-era MacBook (with SSD) started running slow this morning. Thinking that maybe I had too much stuff running, I tried to do a restart. The restart was suddenly going really slow, and it didn't help, so I worked a little and tried to restart again.

The Apple logo would come up, and it would show the progress bar, but it would get halfway, and the MacBook would literally shut off. I would turn it back on, and eventually it would take me to the login screen. But suddenly, it acted like my login didn't exist (I type in my name and password, instead of select).

I was able to log into the admin, and it only had my ex's account, and my admin account, but my personal account was gone.

Because I am an American living in the far southern reaches of the Caribbean (and an ocean away from the nearest Genius Bar), I looked all over (including these forums) for ways to recover. But then I realized that being a Mac-fan, I've become way too dependent on my Mac always working, and found out that I am really a dunce when it comes to anything other than point, click and type.

I think somewhere along the way, I messed up the rest of the drive (or the corruption simply spread, who knows). So now the ONLY place I can access is the disk utility area where I can restore from Time Machine, etc. It won't even try to repair ... it gives me an error. When I try to restore from my Time Machine (which would suck, because idiot me hasn't updated that since May), it says I don't have enough room on the hard drive. And when I try to just re-install El Capitan, the MacBook literally laughs at me, and says it can't do that (and it calls me Dave ... very odd) ...

So now I'm stuck. I can't even wipe the hard drive and start fresh. My MacBook is now a very expensive paperweight.

For the cost of a flight back to an Apple Store, I could almost buy a new MacBook to replace it ... so I am hoping someone will help me, who is not very literate, and has no real other help (my roommate here is a Mac-hater ... it breaks my heart).

Please help me.

Please help me find a way to mount the drive again, so I can do something with it. And if you really could, I would love to be able to restore my account, at least long enough to make one last Time Machine update, and I will then do a clean install if that's needed. Or just something to where I can use my MacBook again.

Thank you!