It seems to me the best you can do is telephone and explain. That probably should have been done in advance of the hearing but... that ship has sailed already. Make contact and explain to see if a new hearing might be set.
If you missed an immigration court hearing, you have been ordered deported. You will need to retain an experienced immigration attorney to fix the issue.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship.