How to determine each number of those contorols?

I have did this work but i didn't get answer.
i put i=1. 
Thx for your answer.

This latest error I can understand!

When i = 0, that line is looking for a label named lbl0 which doesn't exist as your numbering starts at lbl1. Consequently, the First() extension method throws an exception because there are no elements in the sequence.

To correct it, change the line to:

cmd.Parameters.AddWithValue("@clrke_Percent", this.Controls.Find(string.Format("lbl{0}", i + 1), false).First().Text);

Hi everyone
I put this line
 cmd.Parameters.AddWithValue("@clrke_Percent", this.Controls.Find(string.Format("lbl{0}", i), false).First().Text);
 its eeror is "Sequence contains no elements".
rather than
   cmd.Parameters.AddWithValue("@clrke_Percent", lbl[i].Text);// this line it isn't correct.

I can't find anywhere in that code where you're actually using 'lbl' as a variable which is the only situation I can think of which would give you an error like that.

Can you pinpoint on which line the error is occurring?

private void btnSabtClerkEvaluation_Click(object sender, EventArgs e)
        {
            try
            {
                if (lbl1.Text.Trim() == string.Empty || lbl2Takhasos2.Text.Trim() == string.Empty || lbl3Khalaghiat3.Text.Trim() == string.Empty || lbl4Nazm4.Text.Trim() == string.Empty || lbl5Raftar5.Text.Trim() == string.Empty ||
                   lbl6Taamol6.Text.Trim() == string.Empty || lbl7Masouliatpaziri7.Text.Trim() == string.Empty || lbl8Arastegi8.Text.Trim() == string.Empty || lbl9MizaneKhata9.Text.Trim() == string.Empty || lbl10SakhtiKar10.Text.Trim() == string.Empty)
                {
                    MessageBox.Show("Error", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
                else
                {
                    SqlCommand cmd = new SqlCommand("ClerkEvaluation_Insert", conn);
                    cmd.CommandType = CommandType.StoredProcedure;
                    for (int i = 0; i <= 10; i++)
                    {


                        cmd.Parameters.AddWithValue("@clrk_Name", txtNameClerkEvaluation.Text);
                        cmd.Parameters.AddWithValue("@clrk_Family", txtFamilyClerkEvaluation.Text);
                        cmd.Parameters.AddWithValue("@clrk_MelliCode", txtMelliCodeClerkEvaluation.Text);
                        //cmd.Parameters.AddWithValue("@epcnt_Name", "?????");
                        //cmd.Parameters.AddWithValue("@clrke_Percent", lbl1MadrakeTahsili[i].Name.su
                        //cmd.Parameters.AddWithValue("@clrke_Tozihat", txtRaftar[i].);
                        cmd.Parameters.AddWithValue("@i", i);
                        cmd.Parameters.AddWithValue("@clrke_Percent", this.Controls.Find(string.Format("lbl{0}", i), false).First().Text);
                        cmd.Parameters.AddWithValue("@clrke_Percent", this.Controls.Find(string.Format("txt{0}", i), false).First().Text);
                        cmd.ExecuteNonQuery();
                        conn.Close();
                    }
                }
            }
            catch
            {
                MessageBox.Show(".Error", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);


            }


        }
I have som TextBox and Lable when their names are txt1,txt2,txt3... and lbl1,lbl2,lbl3,...
I want variable value be part of Textbox's name. For example i define lbl1 in Form for a Lable's name and in the code i want to say lbl[i].Text. Base on'i' the code choose own lbl and send its text. Insted number i want to put variable
I should define lbl[i], because with 'i' i can send all Lable.Text or TextBox.Text order. I want to say lbl[i] (=lbl1) .Text to send now.

I suspect that there's a confusion in your mind between the name of a variable (or array element) which refers to a Label object and the Name property of the Label object itself. 

Can you post the actual code which is giving you that error, please.

Hi
When i write this line, I get this eeror
"Error2The name 'lbl' does not exist in the current contextD:\Project\evaluation\WindowsFormsApplication1\WindowsFormsApplication1\Form1.cs976119WindowsFormsApplication1"
Because i Want variable value be part of textbox's name. for example i define lbl1 and in the code i want say lbl[i].Text. based on 'i' the code choose own lbl and send its text.
Thx for your help.

So you want to send both the number of the label or textbox and the text it contains?

If so, then how you send it depends on what the stored procedure is expecting so that it can distinguish the number from the text.

For example, if it's expecting both to be sent as a single parameter with the number coming first followed by a space and then the text, you could do: