what year is on the 1099-C - 2019 or earlier. if 2019, you need do nothing until you file for the current year, if prior, seek professional advice. the IRS already could send you a notice and maybe even a bill. A pro can look at the various options to reduce or eliminate any taxation of the debt forgiveness.
I filed bankruptcy in Sept 2018. I completed my tax return for 2018 before April 2019. My refund was sent to the trustee and I received the balance by end of Jun 2019. Then I received a 1099-C in late Aug 2019. I assume I need to file an amended return indicating I was bankrupt and insolvent at the time. This will insure I owe no taxes? But the IRS has not contacted me for anything?