The only way for a student to gain access to a Similarity Report is by logging into their Turnitin account and viewing or downloading the Similarity Report directly.
If a class is no longer listed on your account, then you will no longer have access to the Similarity Report. You will need to speak with the instructor of the class directly to see if they have a copy of the report on hand or can download it from the system for you.
Note: Turnitin does not distribute papers to anyone for any reason. Please get in touch with your institution for further queries regarding this matter.