You cannot get your employer to withhold 2019 tax after the fact, but you can get it fixed going forward---you need to have your employer fix it. For your 2019 return, if you had no CA tax withheld and you lived/worked in CA, you are going to owe. Sorry.
What do you need help with?
Since the state of Texas has no state income tax, I assume no state taxes were withheld. If you owe CA taxes, you will have to pay all the taxes that should have been withheld out of pocket.