If I have 2 HDD's, one with OS and programs (such as SSD) and another with just files, pictures, videos etc. Can a virus on either one of the drives infect the other or are they limited to the drive they are on?
Sure they can infect your MP3 player and mobile phone, and one specifically targets iPhones. I remember back in the early - mid 90's there was a series of reports of a virus that caused your monitor to blow, so it all depends on the virus.
They're especially dangerous when they infect removable media like flash drives.
And they travel across networks (and possibly across wireless networks) to infect shared resources.
Boot into Safe Mode and run a virus scan from there. Safe Mode should keep a virus from loading up and going active.
Best to also have a '2nd opinion' run a scan. The worst kind of infections (rootkits) can hide themselves from an AV scan and even alter how an AV program works in a malicious way.
Download and install Malwarebytes Anti-Malware 1.46 and run that from Safe Mode.
Most of the major security players have a free online scan utility too.