What should I do if I didnt file taxes last year? How would I do that now?

[fanfare]

the tax software for the 2018 tax year is still sold. 
You need a PC or a MAC to run it. 

your state may offer free filing of this year and the previous.,

[AnnetteB6]

You can still file your 2018 return using TurboTax.  However, you will need to purchase and download a version of TurboTax in order to do so.  Any prior year returns must be printed and filed by mail.  They cannot be electronically filed.

Take a look at the following TurboTax article for more information:  How do I prepare a prior year tax return?

@oliviakking