By mistake input not claimed

yes you can claimedin in next return or subsequest return 

As per 16(4): A registered person shall not be entitled to take input tax credit in respect of any invoice or debit note for supply of goods or services or both after the due date of furnishing of the return under section 39 for the month of September following the end of financial year to which such invoice or invoice relating to such debit note pertains or furnishing of the
relevant annual return, whichever is earlier.

Since the invoice for which credit unclaimed belongs to F.Y: 2018-19, I.T.C with respect to such invoice can be claimed on or before the due date of furnishing the return for the month of September,2019 u/s.39(1) i.e. 20th,October 2019