How to generate automatic values inside column?

Question

I know that using Identity we can generate automatic values . but Identity is not a better option for auto generate values becoz when I delete one record inside my table then this table  Identity column does not take deleted identity value when next record inserted inside table.

example : When I delete values from customer cust_id is Identity column 
suppose customer table has 5 records. when I delete 5th record from the table then Identity value is not set with 5 (If you have solution please help me)  and when I insert record inside customer table then Identity column takes directly 6th value.I required it identity must take 5 value instead of 6th when next record insert inside table.Please help me regarding this.Thanks in advance.