Deceased it return filling

Dear CAclubindia,

My father has been filing the IT regularly since 2009. He got deceased in Oct 2015 and Due to other issues, I being a legal heir failed to file the excess tax paid and file the refund. My question now how can I  claim the refund of tax paid and what is the procedure?

I am getting an error as to unable to file online as it says we cannot file online as the date of death is more than the year.

please guide how to go about this?