Return to be filed under which section after time period of revised return is expired..

if an assessee received the intimation u
/s 143(1) for ay 2019- 20 regarding head u/s 10 (proper classification was not made ) (but no income tax de
mand), could not response to such notice ... but now since time of revised return has expired but assessment is not made...

so now under which section this return can be rectified..???