@veteran007
You have to wait until the loss is realized--that is, made real by some final act that either pays you a small amount or declares the stock to be legally worthless. As of now, it is still only a potential loss. If you don't want to wait for the bankruptcy to conclude, maybe you could sell your stock to your broker for $1, that would make your loss real, and the broker would take any upside (if the settlement was more than $1, they would keep it). Some brokers will do this for you, but not all.
When the loss is realized, you report it as a capital loss in Turbotax. You can use it to offset other capital gains. If you don't have any capital gains, you can deduct $3000 of the loss and carry the rest forward to the next year when you can again deduct up to your gains, or $3000 with a carry-forward, and so on.
