can’t view or add comments

I’ve had several people tell me that they havent been able to post comments on my blog, yet just a few minutes later someone completely different will post a comment no problem. when I go to view my blog it says that there is a certain number of comments, but it wont show them. I’ve looked all around my admin area (although i’m DEFINITELY not that computer smart!) and can’t figure out how to change it or what the issue would be that some people would be able to comment and others wouldnt! any advice?