Legal Question in Real Estate Law in California

The new owner of a foreclosed property [like the old owner] has a right to evict the tenants, as long as the owner follows the terms and procedures of any long term lease or rental agreement, if there is one. Unless you have a lease with protection from termination by extended notice required, you are going to be evicted. Check you lease, and negotiate with the owner.

Actually you had three (3) days to get out, which was triggered if and when you were served with a three day notice to quit.

If you don't answer the unlawful detainer, your default will be taken and you will be escorted out of the property much sooner. I strongly suggest you speak to an attorney familiar with unlawful detainer and foreclosure law in California.

You do not specify whether you are/were a tenant with a lease, or exactly what your rights to the dwelling are. Were you the owner? what happened in July when you were trying to "ward off the sale" of your property? Before you were notified of the Unlawful Detainer, were you actually served with a NOTICE TO QUIT or any other kind of notice requiring you to do something, like pay rent or move out? Or was the Unlawful Detainer action the first notice you received? Lots of questions here. The "simple" answer is that unless you were actually served with a NOTICE TO QUIT, they cannot file an Unlawful Detainer action.