My computer is really running slow. I don’t have a lot of pictures or music files loaded on it. Are there any free downloadable reputable software programs out there that will help to speed up my computers performance?

In order to take a major standardized exam on my laptop, I am required to have a clean hard drive, with no data except what is necessary to write the exam. Unfortunately, I am not allowed to use software that blocks access to my hard drive while writing the exam. I really don’t want to lose all of my data and programs — is there a way to move the contents of my current hard drive on to an external drive? Or will I either have to erase everything or get a new computer? I am especially concerned about my itunes library, I have had difficulties after transferring music files between user accounts on my hard drive in the past. Thank you for your help!!!