How to do background verification of an employee (or new joinee) when the previous company is closed?

That is an important question, but we need to ask ourselves what is the purpose of the background varification. Mostly to know if this employee is a fitting candidate for the job and have no bad history as a staff from behavioral point, and experience point; and to make sure that he is as what he is talking about himself. References list shall be requested from the candidate with contact details starting from his last job. If he provided such list this will show you that he is honest and have nothing to hide and you can start from his last work colleagues. If the answers are satisfactory so you can proceed with the hiring process. In this point having the previous company closed it doesnt necessarily mean that the candidate is not qualified as so many reasons can effect this issue. 

Thanks Ola. Appreciate your reply. Actually we had one candidate joined with us last month & he mentioned that the company is closed so he's looking for change. He had shown experience of2years (relevant as per our position) which made him towards selection in Interview rounds. So, do agree with you100% that If we are satisfied with the candidate including Ref checks & Interview screenings, we had let him join us.

Thanks again Ola. Good day.

Regards, Santosh Kuntal, HR, Jaquar.