Sounds like you might have a combination of problems. Headphones most often get static if the headphone jack becomes dirty. In this case, a can of air can be used to blow out any debris and improve the sound quality. The other possibility is that your headphones are faulty in some way. Try plugging them into another device and see if there is still static. If so, you might need a new pair of headphones.
As far as the external speakers go the most likely cause of your problem is a blown speaker, being as the left speaker often cuts out and stops working. It sounds like the left speaker is the culprit of your reduced sound quality. On the other hand the sound card on the device’s motherboard might have been damaged in some way. In these cases, either the speaker or the motherboard will have to be replaced. For more information on these problems and how to fix them please see the troubleshooting page.