UnboxCoin was a cryptocurrency wallet with limited features that just had availability to store Bitcoin and another insufficient number of altcoins. The reasons for this project being closed are not clear yet. But the main deduction comes from the lack of management it uses to have. The company released just waiting, perhaps, so that developers get interested in it, but it doesn't happen.
Currently, the site is on sale. The domain has not a private representation, but it might be within the reach of everyone who wants to pay for it. Anyway, the chances of taking back to life this project are short. And even if that happens, users already disliked the service.
In conclusion, this wallet is not available. So, don't try to look for it since you might lose all your assets, or your data can be affected.