I forgot my pin 5 digit pin to e-file. how do i retrieve it. I'm also not talking about the 6 digit irs pin.

You only need the 2017 AGI  OR  the PIN ... you do not need both. 

leave the AGI field empty, and proceed.

if turbotax has your PIN, it should appear.

NOTE: I'm guessing; that's how other programs do it.