you would not receive a k-1 since it is a C-corp nor a 1099 since the corp itself is responsible for paying taxes on any income it had.  you did not say whether this was your corp (privately held) or traded on an exchange.

the IRS position is that it has to be totally worthless to take a loss. if it is, your loss would be a capital loss equal to your tax basis in it. reportable on schedule d  

Mike, thank you for your quick response. For some reason my earlier question got truncated, so here are some details: It was a privately held C-Corp. Went out of business around Oct.2018. Tried reaching out to owner/president/director for a while but no response...waited till now to claim the losses. Wanted to check if I can claim the stock/equity investment as Ordinary loss (given abandoned corporation, using Sec.165(a) instead of 165(g), and then the debt investment piece (loans I gave the corporation) as capital loss.
Thank you.