You can download QuickBooks and other Intuit products such as Point of Sale, Invoice Manager, and Simple Start from the Internet.

You can register copies of QuickBooks that have never been registered, or you can reregister previously registered copies (including copies that are now discontinued) online or by phone. If using multiple copies of QuickBooks, you must register each copy that has been installed on every computer.

Link to Intuit's Automated Password Reset Tool.