Not able to hear properly from one speaker. How to fix it?

To ensure this isn't a settings issue, go to Control Panel - Hardware and Sound - Sound. Under the playback tab, select your speakers and click configure, then click test. It should play sound from both sides regardless of how they are set up in Windows.

If both speakers function well on the test, you will need to adjust the balance of your speakers.

If you still don't get sound from both speakers during the test, you will need to disassemble your computer (if a guide is not on iFixit, you should be able to find one somewhere online), find which speaker is broken, and follow the wire to the motherboard where it should be firmly connected. If it is not, plug it in and test the speakers again. If it still doesn't work, you will need to buy a replacement speaker.