Lost sound on the left side of my sennheiser PX100 headphone??!

SOURCE: AKG K240S headphones not working well.

A buzz in one ear and no sound in the other 'sounds' like an open connection inside the headphones. The K240-series uses three wires from the pin to the headphones. Try this link to get wiring schematics and disassembly details: http://www.akg.com/site/powerslave,id,7,nodeid,7,_language,EN,cat,11.html

DHE 2008

SOURCE: RS120 Can still hear TV when headphones are on

Ok.. first.. the simple thing is to go into your television menu and turn the television speaker OFF.
Then exit the menu and turn the volume up.. try your headphones now.

Next.. check the back of the TV for a FIXED AUDIO OUT.. plut your headphones into these outputs.. if you have these.. you can simply turn the set down.. and use the volume control on the headphones.

SOURCE: The left earbud of my Bose in-ear headphones doesn't have sound

You probably need to replace the stereo plug on the end that goes into the jack. Most of them are molded on unfortunately but it can be done with a new jack and some soldering skills. There have been lots of people with the same problem on this site so there are already some good explanations of how to do this on here.

SOURCE: Left Headphone not working

well maybe because, you to cheap to by good headphones

SOURCE: Headphones gone quiet

Well, I think you've just blown them. I need more details...what music were you listening to? How loud? Etc.