Well, unfortunately, there really is no surefire way to recover from this. But there are a few things you can do to ameliorate the situation. First of all, reconcile yourself to the fact that the least likely scenario in all the world is that he’s going to call and be interested in you.
Second, stop avoiding him! You may feel awkward facing him, but that is an artificial emotion that you’ve created in your head, and you can do away with it as easily as you’ve created it. Nobody can take your dignity away from you. The next time you walk past him in the hall, smile and nod. Don’t say “hi,” just smile and nod. Don’t refer to your phone number, or ask him if he’s going to call, or apologize, either. Act completely normal, even if you are putting on a total show. When you can walk past him without feeling embarassed or awkward, then graduate to “Hi, (his first name).”
And that’s it for now. After this, it gets a little hazy. I’m giving these recommendations without knowing this guy, although it appears that makes me no worse off than you are. I’m basing it on the presumption that he is a psychologically normal early-20s male similar to all the ones I knew in college. The actions I’ve described are intended to send the message that you giving him your number was an anomolous incident, and you really are a normal girl. He’s already willing to believe you’re a little strange, and that’s why you shouldn’t try talking to him yet. You need to back off, and let your prior actions recede in his memory.
Sorry if this isn’t the “magic bullet” you might’ve hoped for that could land you the guy of your dreams. But c’est la vie. Being rejected is not the occasional thing, it’s the norm. In my fraternity in college we took an informal poll once, and found most of us had to ask out about 3 different girls to get one date. And IIRC, of that 1/3, we got a second date only ten percent of the time.
It is possible this situation could play out in other, less pleasant ways as well. If this guy is a tramp, he could interpret your overture as an invitation to make a booty call. How you deal with that, if it happens, is your business. But whatever you do, don’t go anywhere alone with him unless you know he’s not like that. This is how date rape happens.
And I would recommend, in the future, talking to girls you know who date more than you and finding out how they meet men. Don’t ask guys what you should do; their advice would be self-serving. You are, alas, at an age when dating is most fraught with peril. The one piece of advice I always gave my friends who asked my opinion was “be prepared for some emotional pain and embarassment. There will be NO progress without it.” They usually didn’t listen, and tried to take the easy way out. (Like avoiding people so things wouldn’t be awkward.) It never worked for them in the long run; they just ended up digging a deeper hole for themselves.
You seem to be a person of character though, so here’s hoping you pull through. Best of luck to you.