I've been recording music with my own special set up for sometime now, its nothing special or fancy, it simply suits my needs. All of a sudden my mic input, which I plug many different mics/amps/keyboards into now all of a sudden produces this horrid noise when ever I record. I can open my program and have nothing plugged into the input and it still records that same nasty hissing/popping sound. I have no clue what could be wrong. I've never had problems before.
Not to mention that it also produces the same sound on EVERY thing that is plugged into it. So I can only think it has to do with the input itself, maybe my sound card? Is it possible that a bad cable or particular set up could ruin the input?
 If you place the mic too close to the speakers while being plugged in, due to feedback, you get a high pitched noise. Also due to magnetic interference, problems can occur. Try spacing out your speakers from the input devices (mic, keyboard, amp, etc)
 The sound card could be the culprit. Try removing it & recording from the motherboard's onboard audio inputs. If you get a flawless recording from that, then it's definitely the sound card which is faulty.
it could be a couple of things. Just out of curiosity is it a 3.5mm jack or a 1/4 inch jack socket? Truth is 3.5mm jacks are only good for about 1000 inserts (if you take it out and stick it in 3 times a day it could degrade or break within a year) 1/4 inch are at least 10,000 and they're easily replaceable. It sounds to me like it's the channel itself. Maybe a good idea to stick something into the Line In port and see if that has the same problem (i.e. that its the sound card and not the channel or the settings on that channel) If you dont have a line in, I'd say try what ksampanna suggested and remove the sound card completely and trying from the motherboard, but generally mobo inputs tend to either have a bit of crosstalk (even on the output) and other noise, sometimes even hum because the channels aren't isolated very well. If the line in port doesnt work try adjusting the settings in windows for the channel rather than in the program you're recording in. Oh and what does the noise sound like? Particular noises can actually narrow down the problem, hum, hiss, crackling, some frequencies sounding louder while some are muted (e.g. underwater sound), etc.etc.
I have a feeling it is the sound card because I've have a placement for all of my equipment so that I DON'T get feed back and the same placement is still giving me problems. How could I find out about the jack type? I don't have a line in, just the standard mic and headphone inputs.
As far as the sound goes, I don't have crystal clarity(which doesn't bother me at all considering the quality I do get) So there's always a slight hiss that you hear, even in some professional recordings. Its a loud hum and it tends to pop/crack at the end of each hum. It hums about 3 seconds at a time, cracks real loud, goes back to the regular fuzz for .5 seconds and repeats the WHOLE time it is recording. I don't have to have ANYTHING plugged into the mic input for to do that. By the way this is a laptop, from 2004.. I'm a college student and fixed my girlfriends laptop (this one, mine now) so that I could use it but I'm not entirely savvy when it comes to laptops. Now Desktop/Tower, no issues but before I open it up i just want to make sure of something. I've heard(just heard) that you cannot replace sound cards/gfx cards for laptops because of their motherboards configuration. Before I open it up and pull the sound card out, is it replaceable? will the stock one go back in/do I need to reinstall drivers or will it recognize the hardware?