The lock and pushpin icons are sprites on the following image:
https://forums.macrumors.com/styles/macrumors/uix/sprite.png
AFAIK, everyone gets and uses the same image. So open that link in your browser and see what it looks like.
Here's the same image presented as an image:
If you don't see an array of tiny icons directly above this line, then the sprites-image isn't showing up on your computer, for some unknown reason.
I think the sprites need to be extracted from the larger image using JavaScript. Assuming that's true, it's possible that the script to extract or draw the sprites failed to load, or has encountered some kind of error.
EDIT
I just disabled JavaScript and reloaded the forum-page. The pushpin and lock icons appeared, so now I'm pretty sure the sprites don't need JavaScript enabled. But I could be wrong. Debugging is so much fun.