What if I ignore a civil summons from a collection in North Carolina?

Then a default judgement will be entered against you. That judgement can then be used to garnish your salary or seize other assets.

Don't ever ignore a summons. Always send in an answer to the complaint to the clerk of court and send a copy of your answer to the other attorney - then they can't get a judgement against you automatically. If you ignore the summons, it won't go away, it will only get worse.