SET IDENTITY_INSERT mytable ON

DBCC CHECKIDENT
Checks the current identity value for the specified table and, if needed, corrects the identity value.

Syntax
DBCC CHECKIDENT 
    ( 'table_name' 
        [ , { NORESEED 
                | { RESEED [ , new_reseed_value ] } 
            } 
        ] 
    )

Arguments
'table_name'

Is the name of the table for which to check the current identity value. Table names must conform to the rules for identifiers. For more information, see Using Identifiers. The table specified must contain an identity column.

NORESEED

Specifies that the current identity value should not be corrected.

RESEED

Specifies that the current identity value should be corrected.

new_reseed_value

Is the value to use in reseeding the identity column.

SET IDENTITY_INSERT mytable ON