If Lédger® Live is not connecting to a Nano S, start by checking the USB connection. Use a reliable data-capable USB cable, connect the device directly to your computer, and unlock the Nano S with its PIN. Ledger's official documentation confirms that Ledger devices communicate with desktop software through USB.
Next, make sure you are using the latest official Ledger software. Ledger now refers to its current application as Ledger Wallet, formerly Ledger Live. Close other cryptocurrency applications that might be attempting to access the device, then restart the application and reconnect the Nano S.
If the device is detected but an application cannot communicate with it, open the appropriate cryptocurrency application on the Nano S when instructed. You can also try another USB port or restart your computer.
For persistent connection problems, Ledger provides an official support article specifically covering USB connection issues.
Security Notice: Never enter or share your Secret Recovery Phrase while troubleshooting a connection problem. Legitimate Ledger support should never require your complete recovery phrase.