Speakers are not working at all
Internal drive crashed and now I'm using an external hard disk. Still speaker is not working.
I would recommend fixing the internal drive issue first.
This model comes with a custom blade SSD. Here's the IFIXIT guide to gain access to it: MacBook Air 11" Early 2014 SSD Replacement. IFIXIT sells Apple SSD units but you can use a 3rd party SSD which will be a bit cheaper for the larger sizes. Here's the info for OWC: SSD Flash Storage Options For Your Mac
Once you get the OS installed and any needed updates see if you still have the problem.