Index was out of range. Must be non-negative and less than the size of the collection.

public void bindLead()
{
    SqlConnection con = new SqlConnection(cn.ConnectionStrings);
    con.Open();
    SqlCommand cmd = new SqlCommand("SELECT [LedId],[FirstName],[Company],[ProductInterest],[PotentialRevenue],[Date],[Status],[Owner]  FROM [WebCrm].[dbo].[tbl_Lead]", con);
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    da.Fill(ds);
    con.Close();
    if (ds.Tables[0].Rows.Count > 0)
    {
        grdLead.DataSource = ds;
        grdLead.DataBind();
    }
    else
    {
        ds.Tables[0].Rows.Add(ds.Tables[0].NewRow());
        grdLead.DataSource = ds;
        grdLead.DataBind();
        int columncount = grdLead.Rows[0].Cells.Count;
        grdLead.Rows[0].Cells.Clear();
        grdLead.Rows[0].Cells.Add(new TableCell());
        grdLead.Rows[0].Cells[0].ColumnSpan = columncount;
        grdLead.Rows[0].Cells[0].Text = "No Records Found";
    }
}
protected void grdLead_RowEditing(object sender, GridViewEditEventArgs e)
{
    grdLead.EditIndex = e.NewEditIndex;
    bindLead();
}

protected void grdLead_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
    grdLead.EditIndex = -1;
    bindLead();
}

protected void grdLead_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    grdLead.PageIndex = e.NewPageIndex;
    bindLead();
}

protected void grdLead_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    SqlConnection con = new SqlConnection(cn.ConnectionStrings);
    GridViewRow row = (GridViewRow)grdLead.Rows[e.RowIndex];
    Label lblLedId = (Label)row.FindControl("lblLedId");
    con.Open();
    SqlCommand cmd = new SqlCommand("DELETE FROM [WebCrm].[dbo].[tbl_Lead] WHERE LedId='" + Convert.ToInt32(grdLead.DataKeys[e.RowIndex].Value.ToString()) + "'", con);
    cmd.ExecuteNonQuery();
    con.Close();
    bindLead();
}
protected void grdLead_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    int LedId = Convert.ToInt32(grdLead.DataKeys[e.RowIndex].Value.ToString());
    GridViewRow row = (GridViewRow)grdLead.Rows[e.RowIndex];
    Label lblLedId = (Label)row.FindControl("lblLedId");
    //TextBox txtname=(TextBox)gr.cell[].control[];
    TextBox textLead = (TextBox)row.Cells[0].Controls[0];
    TextBox textCompany = (TextBox)row.Cells[1].Controls[0];
    TextBox textProduct = (TextBox)row.Cells[2].Controls[0];
    TextBox textRevenue = (TextBox)row.Cells[3].Controls[0];
    TextBox textDate = (TextBox)row.Cells[4].Controls[0];
    TextBox textStatus = (TextBox)row.Cells[5].Controls[0];
    TextBox textOwner = (TextBox)row.Cells[6].Controls[0];
    //TextBox textadd = (TextBox)row.FindControl("txtadd");
    //TextBox textc = (TextBox)row.FindControl("txtc");
    grdLead.EditIndex = -1;
    con.Open();
    //SqlCommand cmd = new SqlCommand("SELECT * FROM detail", conn);
    SqlCommand cmd = new SqlCommand("update detail set FirstName='" + textLead.Text + "',Company='" + textCompany.Text + "',ProductInterest='" +textProduct.Text +"',PotentialRevenue='" + textRevenue.Text+ "',Date='" + textDate.Text + "',Status='" + textStatus.Text+ "',Owner='"+textOwner.Text+"'", con);
    cmd.ExecuteNonQuery();
    con.Close();
    bindLead();
}