Under the records menu there is Replace field contents which has a replace with serial number option.. Create a found set of the records you need to fix. Place your curser in the id field. Select replace field contents from the records menu. select replace with serial number. Specify the start and incriment. This will effect the whole found set. Be careful, you can't undo it. If your unsure, try it on a backup copy.
Worked like a charm...thank-you....sorry for the new-bee question....