(a) The court may, upon motion of a party or upon its own initiative, grant a new trial in the interest of justice if there is any error or impropriety which had a substantial adverse effect upon the rights of a party.
(b) A motion for a new trial shall be made in writing and upon notice. The motion shall be accompanied by affidavits or evidence of the essential facts in support of the motion. If additional time is required to procure affidavits or evidence the court may postpone the hearing on the motion for such time as it deems reasonable.
(c) A motion for a new trial shall be made not later than 14 days after entry of the sentence, or within such further time as the court may fix before expiration of the time for filing a motion for new trial.
(d) If a new trial is granted, the party shall be in the same position as if no trial had been held and the former verdict shall not be used or mentioned either in evidence or in argument.