Unfortunately for you, Lost Islands is pretty much dead at the moment - it's a known issue, has been for a long time, and it's looking like it's not going to be sorted - therefore, if you hadn't done the download more than a year ago when it was last updated and working, you will not be able to play the game.
Since Activision basically killed this game, I have heard that if you have spent real money in the game, they might send you a Skylanders character in the mail as a peace offering. However, you will need to reach them via phone and depending on what country you are in, they might have shut down the phone number. I just thought I would pass on this information just in case!!