It's generally not possible to file a Nil ITR-1 return for AY 2018-19 if the deadline has passed. However, you might be able to file if you've received a notice from the Income Tax Department. Alternatively, you can try filing a physical return with a request letter, though you won't receive an acknowledgement and it may be time-barred.
18 January 2020
You can file return of income for AY 18-19 online if you receive a notice form Income Tax Department. You may also file return of income for any year in physical form along with a request letter through Post or by personal delivery in the concerned Income Tax Office and upon receipt of such return if the ITD thinks it fit to take an action u/s 148 then it may proceed. However you will not get an acknowledgement on ITR V for physical return from ITD.
18 January 2020
A notice from ITD can be managed by writing to the concerned assessing officer giving details of income and requesting him to initiate action and issue notice.