How do I let my friend see my Facebook status updates?

There are a couple of things you might mean when you are asking this, so let's go down the list. One possibility is that you did indeed hide your updates from a specific friend: it's doable, but tricky. Another possibility is that you've blocked your friend so they not only don't see your update, but you're no longer friends.

Let's step through 'em one by one, shall we?

First off, you can indeed hide your updates from a specific person, and they'll never know about it, they just won't see the updates. If you've done that, you'll find the settings by going to Account --> Privacy Settings:

Once you're there, quite a few options exist:

Click on "Profile Information" and if you have specific block settings created, here's how it'll look:

Click on the little menu button and you'll see "custom edit":

Choose it and you'll next see:

Since Nora is actually a close friend and was just a guinea pig for this demonstration, I'm going to unblock her by clicking on the little "x" next to her name. That info box immediately becomes empty instead, and I click on "Save Settings" and she can now see me again. That's all there is to it.

Now, if you've blocked your friend, the situation's different. In that case you've actually uncoupled your connection, defriended them, and done some level of them having all of your Facebook info hidden and inaccessible. If that's the case, once you're in the top-level privacy area, click on "Block List" instead.

This is what you'll see if they're on the block list:

In this instance, I have Ed blocked (actually, he's a demo too, Ed's a wonderful guy!). To unblock him, I click on the "(remove)" link next to his name.

Up pops a confirm window:

If that's what I really want to do, I need to click on "Confirm" and he's no longer blocked.

Now, at this point he's also not friends with me, so if I do want to re-establish the connection properly, I'll have to "friend" him again, which means he'll see it and need to approve it. Not so invisible at all.

Hope that helps you figure out what's going on and remedy the situation.