How do I get a 5 digit pin, if I did not file through Turbo Tax last year

[Critter]

You will need the AGI from the 2017 return OR  the 5 digit PIN you used to esign that  2017 return ... if you do not have either of these then you will need to print, ink sign & mail in the return.

Then you will pick a 5 digit PIN to represent your 2018 signature and you can use the same number every year so choose something you can easily remember.