Change the Code like
if (string.IsNullOrEmpty(TextBox1.Text) && string.IsNullOrEmpty(TextBox2.Text))
{
Label1.Text="Nulls Not Valid";
Label1.ForeColor = System.Drawing.Color.Red;
}
else
{
int c=0;
for(int i=0;i<info.getlength(0);i++)
{
if((Info[i,0].ToString()==TextBox1.Text)&&(Info[i,1].ToString()==TextBox2.Text))
{
c=1;
break;
}
}
if(c==1)
{
Response.Redirect("Success.aspx");
}
else
{
Response.Redirect("Failed.aspx");
}
}