Tax filing for previous years

As I understand, it cannot be filed. I shall wait for other views

A belated  return u/s 139(4) can be filed within 1 yr from the end of the relevant A.Y or only in case of regular assessment (before due date) ;a return can be filed. There is no othr prov fr filing old return. hence in ur case it cannot be filed. 

actually, the return for earlier years can be filed:

1.  if the return has a refund due, then you need permission from Jurisdictional CIT for condoning the delay (section 119(2))

2.  If there is no refund, you can file a manual return with the jurisdictional AO.  However, such a return wont be processed but will be kept on record.

3.  If you want to do everything perfectly, then request jurisdictional AO to issue 142(1) notice and then file return in response.  Such a return will be processed too.

According to my opinion returen for f.y.2011-12 can not be filed now.