This would be a fairly inexpensive solution:
RCA Audio Cable
1/4" to 3.5mm adapter
If you have an audio receiver with RCA inputs and a headphone jack, you could use that instead of buying an amp, but you didn't mention any other a/v gear that you might possess.
I know the answer to this is already somewhere on the internet but I've spent hours trying to figure out exactly what cables/adapters I need where as it seems to vary per TV and I'm never sure if the given solution actually works as the asker never follows up.
I have a Phillips 42PFL6704D/F7 (picture of inputs: http://i.imgur.com/4yMHarP.png ; manual here: http://download.p4c.philips.com/files/4/42pfl6704d_f7/42pfl6704d_f7_dfu_aen.pdf ), it has a headphone jack but for some reason sound is no longer outputting through the jack properly (I can't hear voices during movies), how can I use the audio ports on the back/side to output sound to 3.5mm headphones? I want to use headphones for both a bluray player and a Wii.
I would really appreciate it if someone could please tell me exactly what products I need to buy, thanks for reading.