I am also having this problem with my Razer Carcharias headset. It's worked perfectly fine until today and now both my Razer and my other headphones on my laptop only have sound in the right set when fully plugged in.
Both work fine when connected to other devices, and I get sound in both headphones when I stick the plug in just enough for the tip to contact the 3.5mm jack. I've tried using other google searches to figure out what my sound card is in case it's gone bad and checked for driver
updates but neither got me anywhere.
I ran the free windows repair tool that was suggested in another place and it's response to my problem was "external device needs to be plugged in for sound". I got this answer as I was listening to music through the plugged in headset, still only getting sound through my right headphone.
Edit: Wow, I forgot I had someone help me get all my specs when I first signed up for this website. Apparently it's integrated. Can it still be bad? How do I update or repair the driver, and what other things could be causing this?