If your Dell computer does not produce any sound, then it is time to go through some easy steps to determine what the problem is. Start with the most obvious, and if that does not work, use the Dell website's resources to go further.
Check Volume & Cables
There is a saying in tech support, "keep it simple stupid," also known as the "KISS Principle." This is not meant to deride anyone, but rather remind both the tech support and user to look for the most obvious issues first. Check that your audio cable is plugged into the correct audio jack, which is usually either color-coded green or has a headphones symbol near it. Sometimes the cable is plugged in wrong, or sometimes the cable comes out when moving a computer around. Also, check that the sound is turned on. The sound icon is near the clock on your Windows start bar.
Re-Install the Drivers
When re-loading Windows, forgetting to re-install drivers is easy to do. If you re-loaded Windows to a factory install, updating the drivers still could help. Go to Dell's website and search for your computer's model number. If you don't know the number, look for a brand sticker on the side of a desktop or the underside of a laptop. The first link that normally comes up is for drivers. Use the prompts to find your drivers, download and install them.
Bad Sound Card
If you still are not getting sound, the sound card is possibly dead. If the computer uses on-board sound (meaning there is no separate card with sound jacks on it), that is more problematic. That part on the board cannot be replaced without replacing the whole motherboard, normally. In either case, install a new sound card and use its jacks for audio. For a laptop, take it to a technician for fixing.