The only possible way to restore the program is if you already have the installation CD/DVD-ROM because the official website doesn't exist anymore which makes the program as being discontinued. There are downloads on 3rd party websites, but I wouldn't recommend using them because of possible malware infection.
Of course, since this application is rather old, you would miss a lot of features if you plan on keep using it. Choose other alternatives because there are plenty to choose from. Here is a link that will show you some applications from the same category which you can use for your basic or advanced image editing.