There is nothing you can do for the 2019 return now if you are looking to get the stimulus payment ... your only option will be to file a 2020 return next January to get the missed stimulus credit ...
If you qualify you can use one of the 10 IRS FREE FILE options that will be available mid January ... for 2020 your AGI must be $72K or less ... https://www.irs.gov/filing/free-file-do-your-federal-taxes-for-free
