Problem with my 21.5 iMac 2011 i can't get it to work

Question

I never had a problem one with my iMac but someone got on there and I am unsure what the heck she did , she was with my brother in my office and apparently according to my brother she was attempting to download something or something but got nervous cause she was aware i didn't want her on my computer so she just shut it down i suppose mid download (maybe a movie? something ) anyway of course the next day I had all sorts of trouble and was told to go to the "utilities' section thing where I could re install snow leopard that was all fine and all but i think perhaps i had already upgraded to mountain lion, i am not entirely certain if that is a fact or not, it has been quite some time since this whole thing took place but i am having a big project coming up and would prefer to use my iMac rather than my MacBook Pro, just because of the screen actually, oh my gosh, anyway i attempted to re install snow leopard as it suggested it seemed to go just fine, the first time i used the computer after doing so things went just fine the next time i tried to use my computer not so much i was instructed once again to attempt to re install then i think i went to that place where you can just erase your hard drive to begin all over again i thought well that sounds like a much better idea i didn't have really anything in there that was important i didn't have it really long enuf so i thought all right i will do this and that was the beginning of the end for me and I think i may have fatally destroyed my iMac which I loved so much, paid so much for and barely even got to work on really, what a shame, the other shame is that I happen to live in Lake Havasu City AZ not always a bad thing but when it comes to having anything to do with an Apple retailer or even anyone who knows very much about Macintosh products, at least as far as I can tell I am totally out of luck, now if things are terrible enuf that the hard drive is destroyed I do have another one that someone was kind enuf to give to me, I am a bit suspicious because of the fact they just gave it to me and I had no idea what questions to ask in order to know whether this is a good one or not i have some questions there but i suppose i can ask them if it turns out that i need to get a new one installed maybe just maybe someone here can help me out and it won't be this horrible ordeal like I have the feeling it may be. I hope you can be patient with me as I have no clue what i am doing but i am good at following directions and will do whatever steps you give me to do to the best of my ability and hopefully together we can fix my iMac, oh i really hope so. Anyway my name is Carly and so hopefully someone will get back to me there thank you so much for your time and consideration in advance i really appreciate it more than you know.

Answer 1

What is wrong with your Mac?  You still haven't told us what the problem is. Is the computer still under warranty or Apple Care?
the next time i attempted to use the computer it wasn't fine
What do you mean by "wasn't fine".  We can't see your computer so you'll have to describe what your're experiencing in detail without the editorializing.
Download and run Etrecheck.  Copy and paste the results into your reply. It's a diagnostic tool that was developed by one of the most respected users here in the ASC to help identify the more obvious culprits.