I have filed a Income tax return with ITR4 and received a communication about defective return asking to fill balance sheet and profit and loss account. I think I can file ITR1 or ITR2 instead of the lengthy ITR4. Can I still change the form and file a revised return with ITR1 or ITR2
Generally revisions are to be submitted in the same form as the Original. i.e. in your case ITR4.
However, If you were originally required to only file ITR 1 / 2 and have filed a ITR 4 in error, then yes you can file the revised return in a different form.