@anthony340 you would need to amend your 2019 tax return. The deadline is July 15, 2023 to do that.
How much did you pay for the warrants? if they were just given to you (i.e. you didn't pay anything), there is no loss to report.
if the loss was $3000 more than the capital gain you reported in 2019, then there should be a carryover loss and that may cause amendments to 2020 and forward returns to consume the carryover.
