I have a requirement to update the field on closed opportunities(won/lost) without reopening the records.
Please suggest if we do have any way of achieving this task.
Thanks.
Yes you can achieve this.
closed (Lost/Won) opportunity can be updated using workflow. Create a OnDemand workflow which will update field which you wish and run this on closed opportunity. try to see if you get field updated.
I just tried it on one of my instance for closed opportunity and I updated description field. It did updated without reopening opportunity.