Can they file a lawsuit over a debt?
Yes. Creditors and debt buyers can sue consumers that default on balances to them. They want their money back. Really. They are counting on the fact that you will not respond or show up to court. If you do not then they may take a default judgment against you. In California, a judgment can be aggressively collected for ten (10) years and even longer if they keep renewing the judgment. This gives a creditor a long time in which to come after you. Many consumers think that a judgment is just a worthless piece of paper. They think that they can be forced to pay in California. They are wrong.
After taking a judgment against you, they can: