If you "found" these files on the internet or worse paid for them, they are empty and fake.
Not quite sure why you'd automatically jump to the worst assumption.
It's not the worst assumption, it's the most likely assumption. It happens a lot, and is a waste of everyone's time.
If you're unsure about the balance, unsure about what software you used, and don't know the password, it sounds like something isn't right.
They're 100% mine and were on an old USB I was sorting through. I simply cannot remember the password I used.
It would help if you're sure about what software you used. If you used Electrum, it told you to write down 12 seed words when you created the wallet. Find those words and you don't need your password.