Testing the sound on a computer can be done by opening an application which you know is supposed to make sound. Then, check the computer's volume settings to see if the application's audio is functioning correctly.
To check if the sound is working, first turn the volume down. Open a program or web page which is supposed to make sound. YouTube videos, media libraries like iTunes and video games should all generate sound. Once the application has launched, slowly raise the speaker volume, and listen to see if sound is coming from the speakers.
If the speakers are not making sound, open the volume settings. In Windows computers, these settings are located within the Control Panel, while Mac users can find volume options in the System Preferences menu. Make sure that the sound is not set to mute. The volume settings feature a decibel meter, which measures the sound pressure levels emitted from the computer. If the volume meter recognizes the sound generated by the application but there is no sound, there is a hardware issue occurring somewhere between the computer and the speakers. Alternatively, a volume meter which does not recognize sound at all indicates an internal software problem.