It may be that it is in headphone mode, or it may be connected to Bluetooth.

Solution:

Settings-General-Accessibility-Call usage in physical activities (default).

Use the iPhone's headphone jack, turn on the iPod to listen to music, then press pause, press the home button to return, turn off the iPhone (no need to use other third-party software), unplug the headphones, and then turn on the phone to solve the problem. , if it doesn't work and you try a few more times, and it still doesn't work, press and hold power home to perform a hard reset, and then when the white apple appears, pull out the headphones.

When the earphones are turned off, we unplug the earphones, find a needle, and gently poke it into the earphone hole twice. It may be that when the earphones are unplugged, the bounce device inside does not return to its original position. , after we poke it, wrap the needle with toilet paper, wipe the inner wall of the headphone hole, and wipe off the dust covering it.