Only the left speaker works, I have tried many common solutions

I know this problem may have been posted several times but in each post, I never found the solution to my problem.

So now here's the rundown.
I have Windows 7 Home Premium 64bit with a Realtek HD Audio sound card.
Whenever I use several headphones in the front jack, they all work perfectly fine. However, whenever I have my speakers (I tried using 2 different pairs of speakers to make sure it wasn't just one pair being affected) SECURELY inserted into the back green port of my computer, there is sound only coming from the left speaker while the right speaker is playing absolutely no sound. This happened to both pairs of speakers that I own.

I have tried the following and none worked:
- Update drivers
- Disable speaker and then enable
- Switching from back jack to front jack (vice versa)
- Balancing so that both L and R sounds are at an equal level

None of these common solutions that I found on this site have worked. Anyone know what's going on?

When you test the speakers, do you disconnect the headset? But you do know both channels are working, at least on the front ports.

Is this a installed card or one on the motherboard?

Does the Realtek mixer panel show the speakers plugged in?

Yes, I made sure the headphones are disconnected when I have the speakers plugged in. the sound card came witht he computer that I bought. and yes, the computer says that i have the speakers perfectly plugged in.

The headset does work on both channels on the rear panel? I had to set my system to see the headset instead of speakers, after I was asked what I plugged it.

So if the sound card is an add-in card, it probably doesn't have any setting in the bios about what type of audio

I will assume your 2 sets of speakers are independent and not using any common component? And they are self-powered?

Maybe it is a bad plug, if the headset doesn't work correctly...

well the headsets work fine. its just the speakers that are affected. One set of speakers use a USB Cable and the green port cable jack. I had them both plugged in and only the left speaker works.

The other set use a bass box and again only the left speaker works. even though i had the right speaker connected the bass box with all the cables given.

We are sort of getting into the weeds here, but it seems both channels are working from the Sound Card, so it might be something about your speakers, or the setting for that port on the sound card.

Do you have 2 independent speakers that can be plugged in by themselves, or do one or both have to go through another device? If they are independent, have you switched them? Since both sets of speakers are doing the same thing, maybe we could just concentrate on the most basic set.

Sorry about the questions, but it is a little hard to envision your configuration without seeing it.

I understand the difficulty of having to imagine the situation lol.

Well, one set is independent. They just plug into the back port of the computer with a cable and its automatically ready-to-use.
The other set needs to be plugged into a subwoofer bass box and at the same time into the computer.

I'm only assuming its my computer with a faulty sound card because it happened to two sets of speakers so its strange. Maybe its just bad luck.

Well, you said the headphone worked on the sound card..right?

If the card is an Add-in, you might try to turn the system off and unplug it. Then try to re-seat the card, possibly a bad connection.

Most likely but the thing is, I don't know how to unplug a sound card. I guess it's installed inside of the computer because the only plugs I have coming out of my computer are the speakers and the cables for the monitor, keyboard, and mouse.