Hi pranathis012,
i think you are doing wrong. On RowdataBound event of gridview, You can only modify or change the already bind data on run time. i.e. if you want to do anything with rows of gridview on conditional basis like row formatting or any-thing.. so you can do. You should bind data table to Gridview using property
<pre lang="c#">
GridViewObject.DataSource=datatableObject;
and after binding you can change or modify with data.
Regards Rahul