We need more info to properly answer this one for you.
1--when was the lawsuit filed?
2--I'm assuming that the lawsuit took place in CA, not TX. if that is the case, did you live in CA when the lawsuit was filed? In other words, did you live in the state that the case went to court in, when the case was filed against you?
3--Did you ever receive a summons? If so, did you answer it?
4--Did the plaintiff get a default judgment against you? If you did not know about the summons, or if you knew about it but did not show up, then they got a default judgment. If you did not have your day in court because you never knew you were being sued, it changes the answers I would give you now.
5--How long ago were you notified about the garnishment?
6--this is a big one--what are they garnishing? In Texas your wages simply cannot be garnished for a debt, unless the debt is a government related debt such as taxes, federal student loans, etc etc, or child support. You were evicted, and your landlord is after the money...last time I checked that was considered a consumer debt.