Hi @karimhelal
You could check if the headphone jack is OK.
I don't know what type they use in the device but with some there are internal contacts that break when the headphones are inserted so that the audio no longer goes to the speaker in the device but connects to the headphones.
With other types there is a single contact in the headphone jack that when the headphones are inserted they either make (or break) and this signals the audio controller in the device to switch the audio from the internal speaker to the headphone jack.
Here's a [https://www.cuidevices.com/blog/understanding-audio-jack-switches-and-schematics|link] that shows the electrical drawing equivalent of audio jacks that may help to understand what I mean.
Here's the ifixit [guide|158423] guide that will also help as it shows how to access the motherboard where the headphone jack is located so that you can test it etc using a DMM (digital multimeter) to see if it is OK or not when the headphone plug is inserted and when it isn't.
''If the headphone jack is faulty'' (jammed internal operating spring perhaps) it will have to be replaced as it cannot be repaired.
There are multiple types of headphone jacks of all configurations available which will make it hard to find the exact replacement but you can only try. Search [https://www.digikey.com.au/en/product-highlight/c/cui/3-5mm-sj2-series|here] or perhaps [https://www.mouser.com/c/?q=3.5mm%20audio%20jack|here] to hopefully find the correct one. Check the datasheet associated with each jack to make sure that if it is the correct type it will be compatible with the motherboard connections that it will be soldered onto.
''If the jack is OK'' then it will be hard to find where the problem lies. All you can do is trace the jack connections back the the controller to make sure that they're all OK.