The computer originally had an integrated sound card on the motherboard, but later I bought an independent sound card and installed it. After installing the driver, I can see that it is normal from the "Device Manager". There is also a small speaker icon in the desktop taskbar tray, but there is no sound when playing with the player.
This is because a sound card was originally integrated on the computer motherboard, and when an independent sound card was installed later, the original integrated sound card still exists, so it causes a conflict between the two sound cards. At this time, one sound card must be specified. Open "Control Panel" → "Sounds and Audio Devices" in turn, select a sound card for "Sound playback" and "Recording", so that the determined sound card will be used for sound. Of course, the best way is to uninstall or disable the original integrated sound card and only use the independent sound card so that there will be no conflicts again.