I’m sorry you’re in such pain right now but unfortunately there’s nothing you can do. Don’t force a situation with him; otherwise you will completely drive him away.
You haven’t provided very much information (your ages, how long you were together) so I can’t give you something more specific, but here goes:
It sounds like communication may have been a problem with the two of you. If a “stupid argument” seriously jeopardized your relationship there may have been something underlying. Communication is the most important thing in a relationship (however casual it may be). *If* you do get the opportunity to talk with him do it in a neutral place and DO NOT start any sentence with “you always” or “you never”. That’s the easiest way to end the conversation. Keep your tone even and non-accusatory. Start sentences with “it appears” or “it seems like”. Let him have his say and don’t interrupt. If you don’t understand something, ask him if he could clarify it for you. *Don’t* say “Are you saying…”. Very bad.
He may need some time alone to rethink this relationship and you need a breather, too. I’ve had my heart broken several times before and it’s no fun when the situation suddenly changes for the worst and I found myself alone. The future is now so uncertain and many people (me included) are afraid of the unknown.
Since you have no control over his action it’s time to take control over your life. Go ahead and mourn your loss. He may never contact you again and you will have to accept it (*not* like it, just accept it). Start putting your life back together. Make yourself go out and do things, even if it’s just going to the mall and window shopping.
What kind of a support network do you have? I’m sure you friends will do what they can to help you through this. They may be able to see things about you that you don’t and can give you some direction.
Don’t wait around by the telephone waiting for it to ring, hoping it will be him. If he wants to contact you, he will. It’s not worth wasting your life on something that may have, at best, a 50/50 chance of happening. You’ll only make yourself miserable.
Only you can decide whether or not it’s worth waiting for him, but I would always have an alternate set of plans in the ready.
Good luck and do keep posting.