My computer only powers up on Guest Mode. Help!

I own a Macbook Pro, 15" or 13", I'm not sure, from 2010. As you may expect, it's an old computer, so it shuts down when there's an overuse of power or whatnot. So when my computer restarted this time, I didn't think much of it, especially since I had a lot of tabs open, and so I didn't think it would do much harm.

I pressed on the power button again, the sound comes on, so does the light, and the "caps lock" button lit up when I pressed it, so it wasn't a display issue.

The mac logo appears, and shortly after shows the two users that were active, the admin and the normal user, and the Guest Mode. (I have two accounts : the admin to administer but I don't use it as often since if I get a virus it could give it to the other users, and the other for "actual" use.) I typed in my password, and the bar appeared. It started to load, and then about one centimeter on the line, it just turns all black. I wait a few moments to make sure that it's off, and it didn't turn back on, so I suspected that it was actually off thid time.

I should also mention that the keyboard isn't lighting up, and that I dropped my computer (closed, face-down) on the ground earlier.

I power it back up, and the same thing happened. I've tried everything. I looked up little tips (how I ruled out the display issue) and tried logging in on the other accounts (the Guest and the admin), and the admin the exact same thing happens, but the Guest it works. I wonder why this is, and if anybody knows why, it would be great to reply and help me right now. (I'm writing this on the guest)

I saw a similar post talking about a Macbook from 2011, so maybe it's an issue of age. (The comments agreed on this same issue), and that it;s charged 99%.

At a loss,

Lana Melaine