I had an instance where I needed to reset the identity value on a table.

This command will tell you what the next identity value for a table is:
DBCC CHECKIDENT (‘TABLENAME’, NORESEED)

This command will set the next identity value (it sets the value to 1 + the number you enter)
DBCC CHECKIDENT (‘TABLENAME’, RESEED, 0)

I’m not sure what the consequences of doing this on a table that already has records in it.
I imagine you could end up with duplicate values.  I was doing this on a table I had emptied first.