I lost my QuickBooks version 6 disk, but I still have my serial number, registration number, and group number. Is there any way for me to get the application back?
If it's an older version of the application (and it seems that it is), I'm not sure if there are any official sources from where you can download the installer. The best advice that I can give you is to contact Inuit directly (the company that develops QuickBooks Pro) using this link https://help.quickbooks.intuit.com/en_US/contact and asking the support team for assistance.