Hi Ankur,
Perhaps datagridview1.rows(0) is referring to the Header Row of the DataGridView,
Try rows(1) instead:
datagridview1.rows(1).cells(1).text(...);
Also a possibility -
Not clear from the question, but it can also be that the text is inside a control inside the cell, in which case you'd first have to reach the control and then the text property of it.
Cheers,
Edo