yikes!
if you are due a refund, it's 'fools gold' as the deadline to rquest a refund was April 15, 2020. In this case, I wouldn't worry about filing. It won't make a difference.
if you owe, you owe! you can download the 2016 tax forms from the IRS web site. TT doesn't support the 2-16 tax year any longer.