For the past 2 days from multiple locations it hasn't worked.
This one works and I don't know if there are others.
https://live.blockcypher.com/
It does make me ponder a little, would kind of stink of all sites relating to looking up your addresses were down? Should the block-explorer one come back up eventually or could some actually go out of service and never come back up. The instructions on the back of the wallet actually have the block-explorer address on it.
There are many explorers out there. These websites run a node on their server in order to get data out of the blockchain and provide you with visualy nice interface to search through.
For litecoin some other explorers: https://chain.so/LTC , https://chainz.cryptoid.info/ltc/, https://bchain.info/LTC/
If these are down you can do simple search on google, yahoo, bing, duckduckgo or what ever search engine you use and simply search for "litecoin block explorer"
Thanks good to have additional links!