I would guess that the two most widely used musical instruments (violin and guitar) are the easiest to learn from. They are both based on a very simple concept: make one note and play it fast. However, if you have ever attempted to learn how to play a single note using any other instrument: saxophone, flute, piano, or guitar, you know it is not trivial! The notes need to be arranged in a way which is easiest to execute using the other instrument(s). You need to work on the articulation of the note(s) in your mind to learn to play it in that way.
Is there a correct way to play an instrument, given no practice? How?
You need to understand how your own playing is going to match the pitch of the instrument by understanding the relationships between the strings, the bow, and your hand. In order to be able to make a good match, you need to be able to visualize the pitch to make the same stroke that is happening in your mouth. Then you need to work on the speed and the direction of the stroke. Then you need to practice to get good at this, and then after you have learned to make the good sound of the note, you have to practice it in different places. Then you can look at how this note relates to other note, and then get used to playing the same sound in different places that you could never practice before. This is how we can get the most enjoyment and success playing any other instrument, and to learn any other instrument is much more difficult to do, than learning one.
Can an instrument be taught?
Sure, that is one way to learn, because you can just play the notes of any instrument, and then you can put the notes together to be a whole. However, a great way to learn is to do a little practice with a little instrument, at home. It is also very fun, and you can be learning music every week. I also learned it at school using a piano. I was in math class with a piano teacher, but that was a lot of fun. I started out playing, and it was much more fun than teaching.
Can I use an instrument to learn music, if I don’t know how to play it?
No. The best and simplest way to learn any other instrument is to give it a lesson. If you listen carefully you will hear how important it is to practice. If you know how to