the periodic Robinhood statements should have details of the split leaving you with no shares. since there was no sale, it may not appear on the 1099-B
if it your interest is truly worthless at the end of 2019, it can be reported as a capital loss.
the important thing is that the end of the year statement, (not necessarily the tax reporting form) either show no shares or if it does, the value must be $0 according to IRS rules.
on the 8949 input i would put NVCN - worthless
you might want to see this
https://finance.zacks.com/report-loss-worthless-securities-taxes-3180.html
