webstie question

one my favorite websites went off line today for good but there is a mirror still up how would I download the whole mirror site so I had it for a reference to my pc? Is it possible?

Depends on your web browser but most browsers have the ability to set a website as "Available Offline"

Also depending on the website, the functionality may be lost and it may be pointless to do anyway. Such as in a web application with a database backend.

Just google "http downloader" and you should get dozens of results. I've used HTTrack before in the past. It probably won't be perfect but if you're after largely static content, it should work fine.