En mi Mac VERSION 10.13.6, desde hace 3 dias, no aparecen las bocinas internas

Give this "first responder" fix a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

Translation:

miembroJoselo wrote:

On my Mac VERSION 10.13.6, for 3 days, the internal speakers have not appeared It worked fine until 3 days ago, and it has stopped working

You neglected to mention the exact model of your Mac. You can get this information by clicking the Apple menu & selecting "About This Mac".

On older Macs sometimes the headphone jack can go bad with one of the contacts getting bent & shorting to ground which makes macOS think headphones are connected. If you play audio and look into the headphone jack....do you see a red light? If so, then this is most likely the problem.

If you connect wired headphones or external speakers do you have audio through them?

Have you tried restarting the Mac? Sometimes a simple reboot is enough to fix problems.

If you have an Intel Mac, then try a PRAM Reset (hold the PRAM Reset for at least two chimes if possible).