It all depends on what you were on probation for and whether or not your conditions of probation would consider this a major default or breach of that deal. There is no excuse to miss a court date, especially if you were on active probation, unless there was an absolute emergency and the court agrees that you had no way to appear and could not contact the court to ask for a continuance. If you turned yourself in, your probation could theoretically be revoked and your new charges could be enhanced for sentencing for failure to appear. Talk to your lawyer who represented you in the first matter (the one for which you received probation) and see if you can get any new charges dismissed and if your particular offense qualifies for expungement.