These are great questions! Some works of art seem quite anchored in the material world. Arguably, a marble statue like the David is in Florence. But poems, plays, novels, musical compositions, and so on do seem more elusive. Some philosophers who might be called Platonists tend to think that poems, plays, and the like are not themselves physical events or objects. On this view, the Iliad may be thought of as an abstract object that can be acted out, recited, written down, remembered, loved or hated, but the epic poem is not itself a physical thing. I am very much drawn to such a position and have defended it (in a short book called Aesthetics; A Beginner's Guide), but many philosophers resist recognizing abstract, non-physical objects. Such philosophers (who might be called nominalists or conceptualists) might have to identify the Iliad as a complex cultural object that has multiple linguistic and social dimensions. For them, the Iliad's status may depend upon an on-going social practice, but for those of us in the Platonic camp, we think that the Iliad still exists even if all records of it fanish. In such conditions, there would still be truths about the Iliad. For example, in such a post-Homeric world, it would still be true that Achilles kills Hector in battle before his beloved city of Troy. Nicholas Wolterstorff has a good book on such topics called (I believe) Works of Art.
Read another response by Charles Taliaferro
How do novels, plays, or works of music exist? Consider the Iliad. The original copy of the Iliad was lost long, long ago, yet the Iliad continues to exist through its copies. If all original-language versions of the Iliad were to disappear, leaving only translations, one would assume the Iliad would continue to exist. What if all copies of the Iliad in any language and in any material form were destroyed, and we were left with nothing but the memory of the Iliad? Would it then cease to exist, until someone (presumably with photographic memory) decided to write it down again? What if all memory and knowledge of the Iliad were erased, but copies still existed, lying around in old boxes where nobody remembered them? Would it still exist if this were the case? How can we conceptualize the existence of things, like an ancient epic poem, which exist in physical form yet are not dependent on these forms?