ReportDocument cryRpt = new ReportDocument();
cryRpt.Load(@"C:\IFAD-Reports\CrystalReportDemo.rpt");
ParameterFieldDefinitions crParameterFieldDefinitions;
ParameterFieldDefinition crParameterFieldDefinition;
ParameterValues crParameterValues = new ParameterValues();
ParameterDiscreteValue crParameterDiscreteValue = new ParameterDiscreteValue();
crParameterDiscreteValue.Value = textBox1.Text;
crParameterFieldDefinitions = cryRpt.DataDefinition.ParameterFields;
crParameterFieldDefinition = crParameterFieldDefinitions["Product"];
crParameterValues = crParameterFieldDefinition.CurrentValues;
crParameterValues.Clear();
crParameterValues.Add(crParameterDiscreteValue);
crParameterFieldDefinition.ApplyCurrentValues(crParameterValues);
crystalReportViewer1.ReportSource = cryRpt;
crystalReportViewer1.Refresh();