retrieve value from database and display in dropdownlist.

first of all you can try by your self , in which line your facing problem just ask that line alone directly you ask code means that's not good for you.

Any one give a code whatever you expect but you can't understand that logic .

Here what i'm trying to do is i have a textbox in that i enter some text and then click on search button then based upon the search the result to be displayed on DDL.

You write your SQL query

SELECT COL1,COL2,COL3 FROM TABLE1 WHERE COL1 LIKE '%searchedresult%'

 protected void btnSearch_OnClick(object sender, EventArgs e)
    {
        Bind_Projects();
    }

protected void Bind_Projects()
    {
        string Search = txtSearch.Text.Trim();
        DataSet dsProj = //what do you want you fetch taht information                           
        ddlSearch.DataSource = dsProj;
        ddlSearch.DataTextField = "Proj_Description";
        ddlSearch.DataValueField = "Proj_Code";
        ddlSearch.DataBind();
        ddlSearch.Items.Insert(0, "---Select---");
    }