How can I close the fiscal year when there is no period to select after accounting period 24?

If your current accounting period is 24, then this is the last open period
you have in Peachtree.  In order to post transactions to the next period,
you need to close the year for accounting periods 1-12:

1.  Make a backup of your data files and name it yr end 2001.

2.  Select Tasks, System, Close Fiscal Year or Year-End Wizard
(depending on your version of the software).

3.  Follow the prompts on the screen, clicking OK or NEXT. 
Accept the default values for each screen.  Don't try to change anything. 
Peachtree will close your oldest year--the year for periods 1-12. 
The closing process will move periods 13-24 to periods 1-12 and give
you 12 more open periods of 13-24. You will then be able to post to
periods 13-24 of your new accounting year.

-- by Gayle Raines, Director of Training at Baytek, an Authorized Peachtree Resource Center.