What can we do if my husband had a judgement against him but he never received summons to appear in court?

You can't get a judgment against you without service, so there's something not quite right about what you are saying. 

If service was improper, you would have grounds to vacate the judgment regardless of the time it was entered; if, on the other hand, there was proper service, and your husband didn't understand or didn't realize what it was, and the judgment was entered more than 30 days ago, you will have a hard time successfully vacating the judgment (within 30 days, it's almost a given, over that, you need a very good reason to vacate).

You should probably consult with an attorney to determine what the best course of action is.

You can file a "Motion To Vacate Default Judgement".

What probably happened is that a creditor (I assume) of your husband's went to court and when he did not appear he lost by "default".  However, unless his creditor can now prove that your husband received notice of the court appearance and that it was properly served, the judgement will be dismissed.  Unfortunately, with creditor this happens all too often.

Your husband will have to contact the court from which the judgement was issued.  He will need to file a motion to vacate the judgment (this is means filing an appeal to the court on the case).  He can then get it dismissed or "vacated."  Basically, this is the equivalent of stamping a big fat red "VOID" on the judgment paperwork.