Hold down Windows + R keys, type in mmsys.cpl, and hit enter. Do you see the internal speaker listed? If so, please make sure it is not disabled (you can right click to enable it). Also make sure it is set as the default device.
If that doesn't help, reinstall the audio driver from the computer manufacturer's website. If you need help finding the driver, please type msinfo32.exe in the search on the taskbar and hit enter, then share a screenshot of the pop-up, please.