Last year I purchased turbo tax but never filed with it (besides the extension) and forgot to do it past the extension period. Can I still use it? I have the order number

[IreneS]

No - If you are talking about preparing your 2017 return with TurboTax Online.  The online program is only for preparing  tax year 2018 returns. 

To complete a prior year tax return using TurboTax you need to purchase and download the desktop edition of the prior year program (2013 thru 2017) and install it on your computer.  Please click this link:  File Past Years’ Taxes

The web page will provide more information on which product fits your situation.

If you purchased the CD/Download version of TurboTax, you can still download and use the 2017 product you purchased.