|Okay, so I missed a few things you stated - oops. |
Obviously we can't know what your experience and level of expertise is unless you state that, and even if you are more qualified, people often jump to the wrong conclusions or try things that don't make sense, and they could use some info that may not know about or suggestions to nudge them in the right direction.
It's extremely rare for an onboard sound chip to fail. Almost always, there's something else wrong.
Having more computer related education doesn't necessarily make you better at troubleshooting - common sense and the ability to think logically are things that you either have or you don't.
"I'm not using external speakers, I never said I did,..."
I assumed you were because you said this...
"I guess the biggest clue that it was my BIOS was that my system speaker stopped working too."
What you should have said was something more clear along the lines of your mboard was not producing the usual one beep while booting.
For desktop mboards, whether the mboard produces beeps is independant of whether the sound in Windows or whatever operating system is working. The mboard will produce beeps even when there is no hard drive installed if a case speaker is hooked up to the proper pins or if there is a speaker like device for that built into the mboard. There are a few exceptions where you must have amplified speakers plugged into the green onboard sound port in order to hear mboard beeps (you hear the beeps regardless of whether there is a hard drive installed). In either case, the sound software does not have to be working properly in the operating system in order for you to hear mboard beeps. Whether the onboard sound is disabled in the bios has no bearing on whether you hear mboard beeps.
I have no idea whether that's the same situation for laptop mboards.
Software problems in your operating system can certainly cause your sound in the operating system to stop working, and that can be caused by data corruption as well as software conflicts, and could in theory be caused by the effects of malware, but that's certainly NOT common.
Games frequently have more bugs in their programming that most programs do. Games alone can cause all sorts of weird problems.
Small amounts of ram errors can cause weird problems, yet your operating system still works.
A common thing that can happen with ram, even ram that worked fine previously, is the ram has, or has developed, a poor connection in it's slot(s).
This usually happens a long time after the ram was installed, but it can happen with new ram, or after moving the computer case from one place to another, and I've had even new modules that needed to have their contacts cleaned.
See response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:
For a laptop, or netbook, you must remove both its main battery and AC adapter before you do that.
For a brand name computer, see the Owner's or User's manual if you need to - how to remove or replace the ram is usually in that - it may already be in your installed programs. If you can't get into Windows, it may be on a disk that came with the computer, or you can go online and look at it or download it - it's in the downloads for your specific model.
Once you have done that, test the ram.
If you want to try a memory diagnostic utility that takes a lot less time to run a full pass than memtest86 does, this one is pretty good - Microsoft's
Windows Memory Diagnostic:
It can be toggled (press T) to do a standard or a more comprehensive set of tests - use the default 6 test one first - if it passes one pass of that, use the latter one. A few of the tests in the latter set are intentionally slower.
If you don't have a floppy drive, see the Quick Start Information at that Microsoft link for how to make a bootable CD of the Windows Memory Diagnostic (you need Windiag.iso - you don't necessarily need to use the program they mention to add it to the CD).
A failing hard drive may cause bad sectors to be "visible" to the operating system - that will cause problems, and often at first it's hard to pin down what's wrong, because sometimes the Windows swap file uses a data area that has a previously undetected bad sector - sometimes it doesn't.
Check your hard drive with the manufacturer's diagnostics.
See the latter part of response 1 in this:
(thanks to Dan Penny for this link:)
Hard Drive Diagnostics Tools and Utilities
If you don't have a floppy drive, you can get a CD image diagnostic utility from most hard drive manufacturer's web sites, but obviously you would need to make a burned CD, preferably a CD-R for best compatibility, on another computer if you need to.
If the hard drive itself tests okay, any data problems found can be fixed, one way or another.
"...checking my BIOS settings was one of the first things I did, there is no setting to disable sound(unless I overlooked it)."
If there is no setting, then it's extremely unlikely malware could disable the onboard sound in the bios settings.
""I put my HDD in another laptop identical to this one...the sound worked fine."
Then there was nothing wrong with the sound software or the registry entries on the hard drive at that point.
It sounds like from what you stated later that you ran Advanced System Care to clean up the registry after that - if that's the case, it wasn't Advanced System Care that made the sound suddenly start working again, unless something got corrupted between the time you tried the drive in the other computer and when you ran Advanced System Care.
Most registry cleaner programs only remove useless and invalid entries from the registry, by default - they aren't capable of removing valid entries placed there by malware.
If your headphones jack has become defective, it's defective inside the jack, so of course you wouldn't see anything wrong with it externally.