I can't hear the sound - Dell OptiPlex GX270 PC Desktop

First troubleshooting steps, double check your speakers, wires to speakers and power. Next if it is onboard audio check bios with peripheral devices and see if it is disabled. Third device manager is your next stop see if sound card is installed and does not have any errors or exclamation points. If at this point the sound card is installed and looks as if running fine but there is no sound, the next step is double clicking on the speaker in the bottom right, go to options then properties and check mark all the other sound device volume controls and also check the volume control you can find in control panel.