@Rembou

I understand your internal speaker is working fine now

You are still facing the issue with external speaker

Try a different external speaker and check.

If it is still not working then we have to do a refresh and reset

click on start - settings - update and security - recovery - reset this pc - get started 

or 

on start - type here to search - type reset this pc - click on reset this pc on the top  - click on get started 

or

Try windows + r using keyboard
on run window - type systemreset

It will show you keep my files and remove everything
chose keep my files 
chose the account - type the password - click on local reinstall - click on reset 
It will be in progress.. 
login to computer and start using the computer. 
If it is still not working 

click on start - settings - update and security - recovery - reset this pc - get started 
chose remove everything 
click on local reinstall - just remove my files - click on reset
It will be in progress

Note:

If you do refresh ( keep my files ) -  all your personal files like pictures, music , documents , videos  will still be intact.   Only the applications will be lost

If you do reset  ( remove everything )  - you are doing a factory default.   It will become like a day one computer.    It will wipe out everything and take your computer to day one like a new computer. 

You can also do the recovery in an alternative way..

There are two alt keys on the keyboard.  If you look at the bottom row of keyboard you can see the one on the left side of space bar and the other on the right side of space bar.  The alt key on the right side will be looking like alt, alt gr or alt car.  Turn off the computer.  Hold the alt key on the left and tap f10 continuously.   It will go to repair mode. It will show you chose an option, continue, troubleshoot.   If it is not going to repair mode, turn off the computer.  Turn on the computer.  Hold the right alt key ( alt gr or alt car or alt )  and then tap f10 continuously.  It will go to chose an option continue and troubleshoot..

It will show you chose an option, continue, troubleshoot
Go to troubleshoot  -  click on reset this pc
click on keep my files  ( only applications will be lost )   chose your account and type your password   - click on local reinstall  - click on reset
It will be in progress 

If the keep my files option is not working 

Go to troubleshoot  -  click on reset this pc – click on remove everything – click on local reinstall – just remove my files – click on reset 
It will reinstall windows. 

If the just remove my files is not working..

Go to troubleshoot  -  click on reset this pc – click on remove everything – click on local reinstall – Fully clean the drive – click on reset 
It will reinstall windows. 

Note: You can also go to chose an option , continue , troubleshoot by holding the alt key + tapping f10  or alt gr + tapping f10 on the keyboard while turning on the computer.    Once you see the troubleshoot option, you can stop tapping the f10 and stop holding the alt key.    Then you can try the keep my files and remove everything ( just remove by files and fully clean the drive ) by following the steps which was mentioned above.