A creditor filed a judgement against my husband and spelled his last name incorrectly we knew nothing of this until his employer received a wage garnishment notice. HELP! How can they do this?

Is the judgment actually for a debt he owes, or do they have the wrong person?

If all other details were correct, and it was a minor spelling issue, not Jones if it was to be Smith, but if it was Junes and should have been Jones, then minor errors are normally accepted.

Did they get served notice of the law suit that got the judgement ? If not, that is your main issue, improper service if no one was informed about the court action.

Once they have a judgement, they do not have to notify you about a garnishment normally ( a few states require notification of garnishment but normally there is no enforcement)

A creditor doesn't "file a judgment", they file a suit and a court awards a judgment.

If you were never informed about this suit then you may be able to get it vacated because of improper service. However, if this is a valid debt, that will only be a delaying action. They will properly serve you before you leave the courthouse.