If a private limited company has taken your security deposit for stock but failed to start business or return your funds, and is now unresponsive with closed premises and untraceable directors, you have several avenues to pursue. It's recommended to first issue a legal demand notice. If that fails, consider filing a First Information Report (FIR) with the local police against the company and its directors, or a complaint with the Economic Offences Wing. You can also initiate a civil suit for money recovery to avoid limitation issues.