Hi,
I have done the similar thing in windows app Gridview's click event,i want to access grid's selected row's 9th cell value which is a check box,try this and make your logic
string valuechk = dataGridView1.CurrentRow.Cells[9].Value.ToString ();
bool chkvalue = Convert.ToBoolean(valuechk);
if(chkvalue ==false)
assignchk.Checked = false;
else
assignchk.Checked = true;