The deadline is midnight in your local time zone. 

I tried to file mine on Turbo Tax on last filing day of extention around 11:20pm Central Time, But Turbo Tax would not process it.

Is there anything I can do.

@iccle If you have an extension for a 2018 tax return the deadline is October 15, 2019.

@iccle   When?  Back on April 15?  There should have been an error message or code.  Did Turbo Tax not let you submit it or did your efile reject?  Try again, go though the Review and File tabs all the way to the very end and hit the big orange Transmit Returns Now button.   You can efile until Oct 15.  

If you can't efile you will have to print and mail it.  

When you efile you get back 2 emails.  The first email only confirms the transmission.  The second email says if the IRS (or state) Accepted or Rejected your efile.

When you log into your account you should also see the status and if it was Accepted or Rejected, Started, Printed, Ready to Mail, etc.  what does it say?

@iccle  Or are you asking about a 2017 return on extension until Oct 15, 2018 last year?