There isn't really any way you can make them all instantly happy. It's scary for a guy to ask a girl out, and the ones you said "no" to have had their feelings hurt, and probably it hurt their confidence, too. (You said you like them all - so they probably all thought they had a good chance to go out with you.)
Obviously you can't go out with all of them. Well, you could, but they wouldn't like it and people would say nasty things about you.
Now, even if you break up with the one, it won't make the others happy. Because you still turned them down. But as long as you were kind about it, and honest, then you didn't do anything wrong. It's not your fault they all asked you out at basically the same time. Right?
Right now they don't know how to act around you so they probably are trying to avoid having to talk to you. If they're good guys, and they understand that you weren't playing games with them, they will get over it after a while.
Be nice to them but not pushy. If you haven't already, maybe tell them each quietly that a bunch of guys all asked you out at once, you never expected that to happen, and you're sorry if you hurt them but there's just no way you can date them all.
Then back off. They are the ones who took a risk and got hurt, so they are the ones who get to decide when they're ready to be friends again like before.
