The following query only reset the value from last record on wards. but not reset the middle records

DECLARE @max_id BIGINT
SELECT @max_id = MAX(ID) FROM tblnew
DBCC CHECKIDENT (tblnew,RESEED, @max_id)

You need to table identity column reset then run the following query. It can delete the all records from table and reset the identity column value

TRUNCATE TABLE tblnew
DBCC CHECKIDENT (tblnew,RESEED, 0)

above the case only the ID column is not a primary key