internal speakers stopped working but headphones are still working

I have a dell laptop inspiron  3558 with intel core i5 with win 10 ...this morning all of a sudden its internal speakers stopped working after i  unplugged my headphones ..I have used headphones before multiple times with no problems ...in audio settings it shows the speakers are enabled and the sound bar is moving but theres no sound ..I plug the headphones back or external speakers  ,those are  working ..troubleshoot is telling me the inbuilt speakers are working fine and cannot detect any problem ..I tried reinstalling the audio driver ,then restarting , then updating with the new Microsoft hd audio driver ,stopped all enhacements restarting again ,still not working ...is this a mechanical problem or a software problem ? I barely had this laptop for 4 months ...will reinstalling windows solve the problem or what should I do ? is the sensor not working ?