You write "My hard drive had fallen onto my graphics card and a small part of my graphics card and hard drive is burnt. I'm not sure what could be causing this."
That seems quite clear to me. Was there a question beyond that one?
In the future, make your questions clear and end them with the question mark. Your title doesn't lead with what I'm guessing is "How do I repair PCs?"
To that you replace the failed parts. It is sadly that simple. Google "The Dead PC" if you need more background on repairing dead PCs.
So, about a few months ago, I switched computer towers and I had no external issues until about two weeks ago. My computer was on for a few hours in sleep mode. I smelled plastic burning a few minutes after I took it out of sleep mode so I quickly shut it off and found that it was coming from my hard drive. There wasn't any damage on the outside so I waited a little bit and then tried a different hard drive. Within seconds of me turning it on, smoking started coming from my computer. I once again, quickly turned it off. My hard drive had fallen onto my graphics card and a small part of my graphics card and hard drive is burnt. I'm not sure what could be causing this.
My computer is older and was given to me by a friend who built it. I'm going to need my computer again soon.