Short answer: It's probably not copyright you're talking about here, but either a trademark or service mark (trademark used to advertise goods, service mark used to advertise a service). Either can be lost through disuse or expire, so if the company's been out of business and not using it, it may be yours.

Long answer: I'm not a lawyer, and the advice of a competent IP attorney would certainly help you there, but you may want to read up on the trademark application process (like here, or here) and maybe try the search referenced in the first link to see if it's still even registered. If not, go for it.