All the installed programs on a computer can be found if you go to Start > Control Panel > Add or Remove Programs (Windows XP) or Programs and Features (Windows 7). There will be a list provided with all the applications that you currently have installed on your machine. If you can't find the Invoice software there, it means that someone has uninstalled it and in order to use it, you will need to install it again. If the program is on the list provided, go to Start > All Programs. You should be able to find it there. (The default path where all the programs are installed is C:\Program Files. It's a good idea to start your search there)
