handed in wrong paper what the heck do i do now?

Quickly send an e-mail to your tutor/module coordinator/lecturer/whoever's in charge and tell them about the mistake!

Done this a couple of hours ago and sent her my actual essay and told her to go into my folder and see all my original work. Fingers crossed its not too late. Thank you

I honestly feel like shooting myself in the head and crawling 6 feet under ground. Basically for 20% of my biology grade we had to write an essay on stem cells being a cure or not for certain diseases. So all is good i write my essay, teacher says it's okay but all i had to add in was my bibliography so i go to type the essay and bibliography. I typed my essay up but as I was typing my essay up I had another word document opened, an essay written by a scientist about stem cells in alzheimer's which was opened because I had to cite what parts I had taken from his research and then add to my bibliography. So I do that but I accidently printed out the scientists essay instead of my other opened document and handed that in to my teacher who has now sent "my essay" off to the SQA where they will open it up, check for plagiarism and bang theres the full essay right there and then they will be thinking wait thats plagiarism and thats me probably going to fail that class now or they will take away all my qualifications all together.
You can now see why i want to shoot myself in my head (multiple times) How the hell do i explain this if an SQA officer comes around? I mean i have all my written work and my written bibliography before i typed it up and every bit of work is dated but I can see me trying to explain that I simply printed off the wrong document by mistake without proof reading and getting made out to be a liar. What the hell do I do? Apologies for the huuuuuge story but i am freaking out and its okay if you laughed at my stupidity

I hope it all gets sorted out, this sounds like my worst nightmare!

thank you so much, trust me I wouldn't wish it upon my worst enemy

I honestly think this will get sorted. You have all the evidence to back up your story, your teacher saw a first draft, and the actual 'plagiarized copy' you handed in is so obvious, it just looks like an honest mistake. Go and see your teacher in person and explain the situation to them, tell the full truth and you should be okay. It is in no ones best interest to have you punished for this. At the same time though, treat this as a learning opportunity, and make sure you don't do it again!