Laptop no longer sends sound to headphones?

I hear about the laptop loudspeaker boxes everything normal, but I hear nothing more with the headset or headset.

Obligatory question of an IT-lecturer:

Ever restarted '?
Have you ever plugged in other headphones?
Are the headphones set as the primary audio player?
take a careful look at the socket if it has a defect?

Everything already done: / nothing to find

Then let's see if the audio playback via jack was disabled? Otherwise times to the specialist give the part