Scroll down to the bottom of your facebook home page.
You must be on the news feed "most recent" page
in the bottom right hand corner click on edit options
and it will bring up this screen.
Chnage the number 250 to 5000
facebook limits the amount of friends whose posts we can see to 250
regardless of how many friends we have, changing it to 5000 now will
save you having to do this as your friends list increases.
here if you have accidentally blocked some one you can show their posts again.