Calm down and think it through -- sometimes life happens unexpectedly, so consider if it's possible something came up and he's simply unable to respond right now. Lots of things can happen -- catastrophic computer failure's sent many an online relationship into a tizzy. If that's the case, you can work it out.

If that isn't the case, if he's just ignoring you for some reason, then I'd say the fault's with him not with you.