I'd use RECUVA to get your files out and once you recover what you didn't backup, start fresh on that HDD with a partition DELETE!!!! and format.
More at the sticky post to follow. READ:
I am a 12th grade student and today was my computer lab, I took my external hard disk because it contained my school project. However, it turned that all the computers in the lab had virus so my hard disk got infected too and started to show strange things instead of my files,
I used my anti virus and removed the malware but it did not seem to fix the issue,
I can search for my files manually and they are on my external hard disk drive.
Kindly help me fix this issue,