Legal Question in Criminal Law in Missouri

No, I don't believe the person who withheld the letter from you can get in trouble for this, unless you are claiming she stole your mail. If it was just a situation where you mother or girl friend withheld the letter from you (and you live with that person), I don't believe there is a legal remedy.

To get a warrant cancelled, you can either 1) hire an attorney to cancel the warrant and represent you in court for the underlying charge, or 2) turn yourself in to police and pay the bond, then the police will release you (if you have no other warrants) and give you a new court date. Then you can go to court and plead guilty and pay the fine or you can hire an attorney to get your charges dismissed or reduced to a lesser offense.

If you hire an attorney to represent you and cancel your warrant, you won't have to turn yourself in to police, pay the bond, or appear in court.