My 2018 tax return won't download from turbotax as a PDF...how can I get it to download from the website?

If you are using the Edge web browser it will change the file extension from .pdf to .txt.  Change your web browser to either Internet Explorer, Chrome or Mozilla.

To access your current or prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/

Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show.  Click on the Year and Click on Download/print return (PDF)

Or -

When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state. 

This will take you back to the 2019 online tax return.

Click on Tax Tools on the left side of the online program screen.  Then click on Print Center.  Then click on Print, save or preview this year's return.  Choose the option Include government and TurboTax worksheets

Is it downloading as a .txt file by mistake?  If so, rename it to change the file extension to .PDF and see if it opens.

If not, try a different browser to download it.