I try to load http://candybox2.net/?slot=1 but the browser can't load the page...
I had the same problem. I think it has to do with the way the site stores data locally. If you visited www.candybox2.net to play the game initially you cannot use the default load links to load the game. As far as your browser is concerned they are not the same site. You need to load http://www.candybox2.net/?slot=1 instead.
So, if you visited www.candybox2.net your slots are:
If you visited candybox2.net your slots are:
Another possibility is that you cleared your browser cache and the save was lost as a direct result. The game mentions a few things that will cause you to lose your save on its save page:
To keep your save you need to use the same browser (not in private/incognito), same device and not clear your browser cache. If you are changing browser or device, or clearing your cache, get the text save from the save page so you can later restore your save.