Move to reconsider within 14 days of the dismissal. Best to have a lawyer do it, and make sure that everything is100% correct. If missing the meeting is the only thing wrong, and you have never done anything like that before, you will probably have the case reinstated. As I said, if you don't have a lawyer, get one now, as that will show the court that you are now taking this seriously.
You can file a motion to vacate or to reconsider. Whether it is granted is up to the Judge. If you were a no show to the meeting (or meetings) with no excuse, did not file all schedule and other required documents, have previous dismissals for similar reasons, and are not ready to file them now, many judges would not be sympathetic. As stated, it is unusual to have a case dismissed solely because you missed the first creditor meeting. We don't know the rest of the story.