1. The laptop (ThinkPad T570) has sound in the headphones but no sound from the external speakers. I confirmed that the external speakers previously had sound.
2. Open the Lenovo Support website: https://newsupport.lenovo.com.cn/ . Search for: t570, and select: ThinkPad T570. See Figure 1.
3. On the newly opened page, click: Driver Download. See Figure 2.
4. Expand Sound Card, which displays: Realtek Audio Driver (Windows 10 64-bit 1607 and later versions), and download and install it. File name: Audio-n1va114w.exe. See Figure 3.
5. Expand Hotkey, which displays: Hotkey Driver (Windows 10 64-bit), and download and install it. File name: SIhotkey-r0yvu35w.exe. See Figure 4.
6. After restarting the computer, the headphones have sound, and the external speakers have sound.