last date to file refund claiming return..ie if u hav refund, then u can file till 31st March 2012

yes agreed,

if you have refund 31st july is not last date you can file till 31st march 2012

In your case you have to file return on or  before 31st July itself,return filed after that will be regarded as belated return.

In case of return,you need not to attach form 16A or need not to give TDS return acknowledgement code so there will be no problem in fililng return of income however your refund will be delayed due to non filing of TDS return by deductor..