You can use this code -
protected void btnStartTrans_Click(object sender, EventArgs e)
{
foreach (GridViewRow row in grid.Rows)
{
if (row.RowType == DataControlRowType.DataRow)
{
LinkButton theLinkButton = (LinkButton)row.FindControl("lbClose");
if(theLinkButton != null)
{
theLinkButton.Enabled = true;
}
}
}
}