old comments are not visible…I'm sure I turned something off..

Hello,

I have 10 years of posts on my blog. In an attempt to limit spamming, I think I turned off all the comments. I still want them visible for people browsing but I don’t want people to be able to still leave comments.

Currently when you look at an old post, it doesn’t even show that comments were left when I know there are some.

How can I turn these back on?