Revised return

I have filled the IT return of AY 2011-12 on 31-03-2012 with zero tax and no refund nothing was shown in 26AS also. Now the case is that there was an TDS dectuion for the assement year but PAN was worngly enter and so it was not shown in 26AS now PAN is rectified and it is show in 26AS also. so what can i do to get IT refund..??

As the return was filled late it cannot be revised so i have to file a rectification.???