Dell Inspiron 15 5559 Audio - Right Speaker has low volume while the left speaker functions normally

Hello.You didn't mention the headphone jack, so if you have not yet done so, plug in headphones and see if the balance is okay in them. If the headphones check out okay, then most probably it's a problem related to the speakers.

The test for speakers is the ePSA audio test. It is a hardware test, which means that if the test  tones are very low in the right speaker, but normal in the left speaker, then there is hardware failure somewhere, related to the right speaker.

If both speakers sound normal during the test, then the problem is in the software. Do the usual things like re-install the audio driver, check the balance levels in the Sound properties, try different audio sources, etc.

Re-installing the audio driver resets the settings to their default configurations, so if you do it then you don't have to bother with things like volumes and balance settings, because they will be okay.(Also if the balance is okay through headphones, then it should be okay through the speakers too.)

Here is how to do a simple driver re-install:

1.    Open the Device Manager.
2.    Expand the "Sound, video & game controllers" category.
3.    Right click on "Realtek High Definition Audio".
4.    Click "uninstall".
5.    Do not check the box to “delete the driver software for this device”.
6.    Restart the computer. Windows will detect your device and re-install the driver. The driver is re-built from files that are in a folder on the hard drive. The reason this process fixes some audio issues is that it resets the driver settings to their default configuration.

If the laptop is still under warranty, remove all media players except Windows Media Player before contacting tech support, or you could be denied warranty service on the speakers.