1099-C

That doesn't go on your return.  You can't write it off or deduct it.  Did you get a court order?  You might be able to deduct a bad debt.  My old notes say....

Enter a Bad Debt under

Federal Taxes (or Personal for H&Bversion)

Wages and  Income (or Personal Income for H&B)

Choose  I'll choose what I work on

Then scroll down to Investment Income

Then Stocks, Mutual Funds, Bonds, Other - Click Start or Update

Then Stocks, Mutual Funds, Bonds, Other - Click Start or Update

If you see a screen that says….Did you have any of these Investment Sales say YES

If you have a screen showing your Investment Sales Summary - click on + Add More Sales

Next screen should ask Did you get a 1099B - say No

Next screen is Choose the type of investment you sold - Pick the Second One

Uncollectible Debt

You can only deduct up to 3,000 (1,500 MFS) loss per year after any gains you have.  The rest you will have to carryover until it is used up.

See https://turbotax.intuit.com/tax-tips/irs-tax-return/how-to-report-non-business-bad-debt-on-a-tax-return/L1mUzQFtB

See also https://www.irs.gov/taxtopics/tc453