childsupport was modified while in hospital missed court date taken fromm my ss check which leaves me 300.00 to live on.

If it is under 30 days since the court made a ruling and not all of the evidence was presented you could try to submit what is called a Motion to Correct Errors.  If it has been more than 30 days since the ruling and you knew about the hearing, but did not file a Motion to Continue, then you may be stuck with the decision.  The first thing you need to do is to get a copy of the Court Order to determine what exactly happened and what numbers where used in modifying child support.  After, that you should try to set up a consultation with an attorney to see if this is something that can be undone.