This may be a difficult situation to handle on your own. You may want to consider consulting with an attorney who handles matters like these.
If you want to avoid an eviction, you will most likely need to negotiate a deal [cash for keys] with either the attorney who's already ignored your call or, perhaps, with a realtor who has come by your house on behalf of the new owner [likely the foreclosing bank].
First, however, if you want to play it safe, you should file an answer to the unlawful detainer summons & complaint. If you don't file an answer to the unlawful detainer complaint within five days of when you received it, your default may be taken and you could be evicted in a matter of days.
Essentially, your filing of an answer is a tool to buy time. Once you've filed the answer, you will then have at least a week or so to try to hammer out a cash for keys agreement.
While you may be able to navigate this on your own and get decent results, it is also possible that you will soon find yourself frustrated and confused -- and uncertain as to how to proceed.
I understand how stressful and challenging your current situation must be. I wish you the best of luck.