You probably have noticed already that some of your friends' updates are missing on the News Feed. This happens because Facebook "predicts" which friends from everyone you have added interest you the most and will only show those people on the news feed.
If you're one of those people who want all their friends' updates back on the News Feed, follow these steps:
Step 1: Go to your Friends list.
Step 2: Hover your mouse on the "Friends" button beside each person and click Settings.
Step 3: Then click All Updates.
Now you'll have all your friends' updates back on your News Feed. The boring thing about this is that you have to do this to all your friends...
I haven't found a way to make it to everyone at once but I'll share it with you as soon as I find it out.