That's the on-board soundcard. To replace it you would have to get a separate PCI card.
Now...just curious...but in your original post you mentioned a guitar AMP. As in power amp?? Yeah, you could have easily blown your sound card by putting a powered signal into the mic jack. That microphone port is only meant for line level input. This is only around a volt a most. Your guitar amp can put out MUCH more than that if you were using the powered output. You may just have been very lucky in the past by having the volume turned down very low.
If you were instead using the line-level output from the amp, it is still possible you had a short in the amp that sent a high-voltage spike to the mic input on your computer. Either that, or the mic jack's terminals finally wore down and are not making contact to the connector.
In summary, it could be either a physical problem with the jack (i.e. the leads broke), or an electrical one (it got zapped). Just add a new PCI or PCIe sound card to your computer and you should be good to go.
