1. Use a poke: There will be a small hole at the back of the background music controller. You can insert it with a fine-pointed object (such as a poke) and press it for a few seconds. Doing so can trigger a hidden button or switch and restore the device to factory settings.

2. find the Reset hole: some background music controllers may have buttons or holes marked with "reset", "FactoryReset" or similar words. The reset operation can be performed by inserting a fine point into the hole and slightly pressing it for a few seconds.