How can I solve this error incorrect syntax near the keyword 'user'

protected void Button1_Click(object sender, EventArgs e)
       {
           string et = signupemail.Text;

           SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
           conn.Open();
           string checkser = "select count (*) from [user] where email ='" + et + "'";
           SqlCommand cmd1 = new SqlCommand(checkser, conn);
           int temp1 = Convert.ToInt32(cmd1.ExecuteScalar().ToString());
           conn.Close();
           if (temp1 == 1)
           {
               Response.Write("already exist");

           }
           else
           {

               SqlConnection con1 = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
               int x=0;

               SqlCommand cmd = new SqlCommand();
               cmd.Connection = con1;
               con1.Open();
               cmd.CommandText = "insert into user(name,email,password,sponserid,upline1,upline2,upline3,upline4,wallet,phonenumber) Values(@name,@email,@password,@sponserid,@upline1,@upline2,@upline3,@upline4,@wallet,@phonenumber)";
               cmd.Parameters.Add("@name", SqlDbType.VarChar).Value = name1.Text;
               cmd.Parameters.Add("@email", SqlDbType.VarChar).Value = signupemail.Text;
               cmd.Parameters.Add("@password", SqlDbType.VarChar).Value =pass2.Text ;
               cmd.Parameters.Add("@sponserid", SqlDbType.VarChar).Value = "csvf";
               cmd.Parameters.Add("@upline1", SqlDbType.VarChar).Value = "bhghg";
               cmd.Parameters.Add("@upline2", SqlDbType.VarChar).Value = "bhghg";
               cmd.Parameters.Add("@upline3", SqlDbType.VarChar).Value = "bhghg";
               cmd.Parameters.Add("@upline4", SqlDbType.VarChar).Value = "bhghg";
               cmd.Parameters.Add("@wallet", SqlDbType.VarChar).Value = x;
               cmd.Parameters.Add("@phonenumber", SqlDbType.VarChar).Value = phone1.Text;
               try
               {
                   cmd.ExecuteNonQuery();
                   con1.Close();
                   Response.Redirect("profile.aspx");
               }
               catch (Exception ex)
               {
                   string msg = "Insert Error:";
                   msg += ex.Message;
                   Label1.Text = ex.Message;


               }
           }






       }