Your remedy is to file a motion to set aside default (and vacate default judgment if a judgment has already been entered). It might also be possible to get the plaintiff to stipulate to setting aside the default, to obviate the necessity for a motion.
Unfortunately, there is no Judicial Council form for a motion to set aside default and to vacate default judgment. If you don't hire an attorney, you'll have to specially prepare it. Here is a link that will give you some helpful guidance:
This was prepared by the Ventura Courts Self-Help Legal Access Center.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This Avvo.com posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, please consult with your own attorney.