You have yet initialized your Ledger device, and maybe have yet made some transaction. But now, when you connect your Ledger device and launch the Ethereum Wallet Chrome application on your computer, the application doesn't open, as if your device weren't recognized.
First, make sure that you don't run any other Chrome extension, and launch the Ledger Wallet Ethereum application on your computer
Disable the "browser support" setting in the Ethereum application of your Nano S or your Blue. This setting must be off to let your Chrome application recognize your device, and on when you want to use your device with another application like MyEtherWallet.
If it still doesn't work, you can try to
- uninstall and reinstall your Ethereum Chrome app
- uninstall and reinstall your Ethereum app on your Nano S
This issue can also come from a bad data connexion, even if your Nano S seems to be properly powered. Then you can try to
- try with another USB cable
- try on another USB port
- try on another computer to see if the connexion issue comes from your computer