You can file your return for F.Y10-11 but penalty can be levied upon you by your Asessing officer, so it is advisable not to file return for F.Y 10-11,
You can file your return for F.Y 11-12 upto 30th july and if u still not able to file it u can file it upto 31.03.12,but if you will file after that sec 139(4) is attaracted.
30 July 2012
PENALTY OF rS. 5000 SHALL BE LEVIED UPON YOU CZ OF LATE FILING OF RETURN, FOR F.Y 10-11, LAST DATE OF RETURN FILING IS 31.07.11, BUT U CAN FILE UPTO 31.03.12, NOW U CAN FILE BUT PENALTY MAY BE LEVIED UPON YOU BY THE A.O.
12 August 2012
In your case for AY2010-11, you need file return and no penalty can be levied. AY 2011-12, you are covered by ITD circular where assessee with income less than Rs.5,00,000/- need not file any income tax return. So do not worry.