If you receive any notice from department for non-filing of your Income Tax Return for A.Y 2017-18 then you can file your ITR in response to that notice otherwise you can not.
yes, you can file your return of A. Y. 2017-18 But for this you will file condonation request with your jurisdictional CIT for delay in filling the ITR.
No.... In normal provisions we can't file ITR for AY 17-18.
But, In case you got any notice from ITD as per Mr. Tarun Kumar's view or Any refund claim or Loss then You can file Condonation f delay as per Ms Deepika Yadav's view...