If you got your grades and didn't get the grade you were hoping for, here's some possible reasons why:
1. You did poorly on the tests and/or papers.
2. Your attendance brought your grade down (see syl.).
3. I didn't receive some paper (s); I might have emailed you about this and you did not respond.
4. You plagiarized all or part of your paper -- i.e., you took it from the internet: you t0ok someone else's writing and thinking and presented it as if it were your own -- and so you failed the course (see syl.). Plagiarism will not be tolerated at all. To see how I would find out if your paper is plagiarized, google some of the more "interesting" sentences in your paper. If they are found online, then your paper is most likely plagiarized.
On the other hand, if you did well on the tests and papers and did your own work on your papers, you probably did quite well! :)