Salary return 19-20

I think you are asking about Salary TDS return for F.Y 2019-20 form 24Q
If you have not any TDS deduction (i.e NIL TDS payable) than you can file "NIL TDS declaration" online for first 3 quarter instend of TDS return.

And You can file Salary TDS return for Q4 for F.Y 2019-20 (if there is any TDS liability) but with late fee and interest,if any as due date is already passed.