I mean the problem with it being LDR is all you can really do is just msg and ask if she's okay which you've already done. I'd personally give it more time myself and don't think the worst right now. We all get busy and can't be on the computer all the time for whatever reason. I wouldn't think the worst of things. If you don't hear back in a couple of days can send another msg, but try not to look overbearing. I don't know how close you two are or how long you've been talking, but depending on that depends on how you come across with multiple msgs; also depends on the person.
Anyways as I said just play it by ear and see what happens msg her after a little more time has passed. The downside of any relationship is even if you feel you connect with someone you're still individuals, so you can only do so much. Don't think the worst just yet.