ITC claim related( Ecommerce business)

I have closed my business and no sale invoice create in dec month but I sell my artical in nov month all the bill is B2C . I submit the return on 10th dec. after submitting the return many bill are return( amount is 2.5lac). how can I claim it's ITC because I have already submitted nav month gstr1 and in dec month no sale generated. please help

can i amendment nov month Gstr1 to reflect those bill( Return)