If you are looking for the code to retrieve data based on Datetime field you can use below code

private EntityCollection RetrieveData(DateTime _Date,IOrganizationService _iService)

        {

 QueryExpression _Query = new QueryExpressio{

    EntityName = “EntityName”, //Replace with entityname

    ColumnSet = new ColumnSet(“AttributeName”), //list of fields

         Criteria =

              {

              FilterOperator = LogicalOperator.And,

              Conditions =

                  {

                new ConditionExpression

                {

                 AttributeName=”_issuedate”, //Replace Condition attribute name

                 Operator=ConditionOperator.Equal,

                  Values={_Date } //Replace condition value

                 }

                  }

               }

           };

         EntityCollection _Entities = _iService.RetrieveMultiple(_Query);

Return _Entities;

}

 Enjoy !!!