The short answer is you should pay for the bills now, and try to repair your credit, and pursue your old employer later. If you don't care about your credit, then try to pursue Circuit City now. You will have to file a claim in bankruptcy court. Go to this site for more info on the Circuit City Bankruptcy. http://www.kccllc.net/circuitcity
Realistically, your chances of getting money from Circuit City are close to zero.
I concur with Mr. ElDabe. You may also want to see if the company's workers compensation insurance carrier may be willing to pay the bill. You should consult an attorney about the matter and for any specific legal advice. If you can't afford an attorney, you may wish to contact the free Debt Collection Clinic operated by the Voluntary Legal Services Program of Northern California in Sacramento at (916) 551-2102. (See http://www.vlsp.org/debt.asp.)
In addition to what has already been suggested, you may want to consult with the Department of Industrial Relations and see whether you can make a claim to the uninsured employers fund. Try looking at http://www.dir.ca.gov/DWC/claims.html. Good luck.