Open *file explorer*.  

Select the drive you want to search (generally *C* - unless you have a server) 

Over to the right, type in the Client Number of one of your clients.

Hit enter, let it churn a bit - depending on how much info you have on your drive.

Soon will appear a list of all the file with THAT client number.

Look for XXXXX.ID9... beneath that will be be data path showing where your proforma'd files are.