Switching on the speaker on your phone depends on the specific model and operating system of your device. However, in most cases, it can be done as follows:
Check that the volume on your phone is set to a high enough level.
Usually, there are separate buttons to adjust the volume on the side or top of your phone. You can increase the volume by pressing the "+" button.
Go to "Settings" on your phone.
Find the "Sound" or "Sounds and notifications" section.
Make sure the sound level is set to high.
Make sure your phone is not in silent or "silent" mode.
Many devices use a switch on the side of the phone to switch the silent mode on/off.
If your issues are related to media playback (such as music or video), make sure the app you are using is not in pause or silent mode.
If after these steps the sound still does not play, you may have a hardware problem with your device and you may want to contact the manufacturer's service centre or get support from a specialist.