How to upload mp3 files in asp.net 3.5

How you saved in the database? From you question this is not known.So I can see two way you can download or save the mp3 file. I will go through them in both ways.

1. If you only save the path of the file. In this case your file should be mapped in a specific folder in you web site. Then map the file name and covert the file to binary array. Like this

string mp3FileName = "E.T - Kety Perry.mp3";
string mp3Path = Server.MapPath("~/mp3/" + mp3FileName ); // Note: I am assuming that you have "mp3" 
folder and "E.T - Kety Perry.mp3" in your root web folder.
byte[] mp3 = System.IO.File.ReadAllBytes(mp3Path);

2. If you save the actual file as binary in the database, read the file as memory stream from the database. The following code some how will help you do this

string mp3FileName = "E.T - Kety Perry.mp3";
       using (SqlConnection connection = new SqlConnection("connectionString"))// Replace based on your Connection srting
       {
           connection.Open();
           // Assuming that you do have a Table called Mp3Table with Mp3File(varbinary(MAX)) data type and Mp3FileName(nvarchar(50)) data type
           using (SqlCommand command = new SqlCommand("Select Mp3File from mp3Table Where Mp3FileName='" + mp3FileName + "'", connection))
           {
               SqlDataReader reader = command.ExecuteReader();
               while (reader.Read())
               {
                   byte[] mp3Bytes = (byte[])reader["Mp3File"];
               }
           }
       }

So save the file to your web site you should have a mechanism to upload the file.How? look the following code.Note you should have FileUpload control in your web page.

if((mp3Uploader.PostedFile != null) && !string.IsNullOrEmpty(mp3Uploader.PostedFile.FileName) && mp3Uploader.PostedFile.ContentLength > 0) {
    byte[] mp3Bytes = new Byte[mp3Uploader.PostedFile.ContentLength];
    mp3Uploader.PostedFile.InputStream.Read(mp3bytes, 0, Convert.ToInt32(mp3Uploader.PostedFile.ContentLength));
}

Then same the mp3Bytes to the database Or Write this binary to your favorite web site directory. How?

System.IO.File.WriteAllBytes(Server.MapPath("~/mp3/"+ System.IO.Path.GetFileName(mp3Uploader.PostedFile.FileName)), mp3Bytes);

Or to Database

string mp3FileName = "E.T - Kety Perry.mp3";
        using (SqlConnection connection = new SqlConnection("connectionString"))// Replace based on your Connection srting
        {
            connection.Open();
            // Assuming that you do have a Table called Mp3Table with Mp3File(varbinary(MAX)) data type and Mp3FileName(nvarchar(50)) data type
            using (SqlCommand command = new SqlCommand("INSERT INTO mp3Table(Mp3File, Mp3FileName,Picture) values(@Mp3File,@Mp3FileName)", connection))
            {
                command.Parameters.Add("@Mp3File", SqlDbType.VarBinary);
                command.Parameters.Add("@Mp3FileName", SqlDbType.NVarChar);
                command.Parameters["@Mp3File"].Value = mp3Bytes;
                command.Parameters["@Mp3FileName"].Value = mp3FileName;
                command.ExecuteNonQuery();
            }
        }

These are the things that you basically do.

Good luck.