Sounds like a bad/dirty volume control in the speakers.  Unfortunately, if it's out of Dell warranty there isn't much hope to get it repaired.  Speakers are in the typical computer component "not repairable" category.  Most speakers are not designed to be repaired and you have to "break open" the unit to get at the parts.  Then there is the problem of getting an exact replacement or a replacement that will fit.  Finally, if they were "repairable" the cost to get them repaired can easily exceed the price of a new replacement set.

One "trick" to clean to temporarily clean a volume control  -  with the speakers powered off, rapidly run the control from zero to max back and forth about ten times.  That will clear a bad contact many times and at least get you going for a little while longer.  However, bottom line start looking for a new speaker system.

I'm not trying to drag the thread on, but I have a headset plug in on the front of my computer and tried plugging it in there and seeing how it is, and my speakers muted and the sound went into the headset. That was the first time it did that, usually there's music coming out from the speakers even if I have my headphones in (if I have the speakers turned on of course). Does that turn any tables, or do I need to buy new speakers?

I have the same problem. Turned the knob back and forth many times. Tried to remove screws and volume knob and open speaker bar. Had it working early on for a while but had to move the computer and volume problem is back. turn it on and volume is high and only adjusts up to louder from there. Won't go low enough to turn sound almost off. Other speakers I have work but they only plug into green port on Soundblaster extreme music on my XPS 400. Seen this in forums going way back but not much help from DELL guys. HELLOOOOO DELL

Plugging into the headphone jack is supposed to mute the speakers.  That is the way it's designed to work.

You never noted it, but What Model PC?  What Operating System? and what type of sound "card" do you have?  Integrated (on the motherboard) audio or do you have a separate sound card (SoundBlaster) and if so what is the model number of the sound card. 

With the speakers not muting when you plug in the headset sounds like you may have a separate sound card, but the integrated audio is still enabled and where your front panel headset jack is connected.  If this is the case, you will have conflicts and could even have the high volume problem. 

Sleeperguy, do not hijack this thread, even if you have the same problem start a new thread so as to not interfere with the original posters problem.  And, this is primarily a (non Dell employee) users helping users, it's not a "direct line to Dell" so your request for help from Dell will fall mostly on deaf ears.