This is your code.
string str2 = employNoTxtBox.Text;
MySqlConnection MyCon = new MySqlConnection("server=localhost; Database = nikz; user id=root; password=nikhil; pooling=false;");
MyCon.Open();
MySqlCommand command = new MySqlCommand();
command.Parameters.AddWithValue("@EmpNo", str2);
command.Connection = MyCon;
command.ExecuteNonQuery();
MyCon.Close();
MyCon.Open();
string connectionString = "server=localhost;" + "database=nikz;" + "uid=root;" + "password=nikhil;";
MySqlCommand command1 = new MySqlCommand();
command1.Parameters.AddWithValue("@EmpNo", str2);
string sql = "SELECT * FROM LFT_Employees WHERE Emp_no='" + str2 + "'";
MySqlConnection connection = new MySqlConnection(connectionString);
MySqlDataAdapter dataadapter = new MySqlDataAdapter(sql, connection);
DataSet ds = new DataSet();
connection.Open();
dataadapter.Fill(ds, "LFT_Employees_table");
connection.Close();
dataGridView1.DataSource = ds;
dataGridView1.DataMember = "LFT_Employees_table";
try adding this line to your code at Last Line. This will perfectly work.
dataGridView1.DataBind();