"was purchased via an asset sale and us common stock shareholders got zilch"

Just based on this (I am not a lawyer or giving financial advice), I'd guess that you can have legal standing to your share, which is probably $0. Investors often have preferred shares, and since it was an asset sale, it doesn't sound like things went well. The shares you bought were holding your place at the very back of the line, and the money ran out long before you. Your shares are probably literally worth $0. Consult a tax attorney or CPA to figure out if you can write off some losses on taxes, maybe?

Preferred shareholders are first in line. The assets got sold, they got a fraction of their investment returned (if anything...) with nothing left for the common. I had this happen to me, as well. It's, by far, the most likely outcome, so don't be surprised you didn't win the startup lottery.