Current Year and Last Year statistics, for both customers in Receivables, and vendors in Payables, are determined by the timing of running Year End Processing. Whenever Year End is run, the Current Year statistics get moved to the Last Year values, and then are reset to zero for the new year. Every time a transaction is posted, it updates the appropriate YTD statistic fields. Period End processing should not affect YTD or LY statistics at all, only the Period to Date values.

These values are stored on the customer record directly, and I would advise against restoring just the customer data files from a backup.

Customer statistics can be edited or imported, if you set the Company Profile to allow editing statistics. If you wish, you could open your data backup, export all the desired YTD and LY statistics to Excel (from the Export Customers process), and then import this file into today's data using the Import Customer process.

Another option is to purchase the 3rd Party add-on program, the 'Adagio Toolkit' from Dakota Software, and the particular process to Recalculate Customer (or Vendor) Statistics. This process is easier to do, and determines the statistics values from transaction dates rather than the timing of running Year End, but of course costs extra to buy. If you rely on these statistics values, the Toolkit add-on is worth considering.