I argued that the sculptures were restored after damage, possibly from an earthquake, in the Hellenistic period, then again in the Roman period, and a final time after a fire damaged the Parthenon in Late Antiquity.
I'm trying to organise my files, and have been promising William St Clair this information for a while, so here goes.
There are almost no mentions of the Parthenon in ancient texts, and even Pausanias skimmed over it in his multi-volume guide to Greece:
[1.24.5] Their ritual, then, is such as I have described. As you enter the temple that they name the Parthenon, all the sculptures you see on what is called the pediment refer to the birth of Athena, those on the rear pediment represent the contest for the land between Athena and Poseidon. The statue itself is made of ivory and gold. On the middle of her helmet is placed a likeness of the Sphinx – the tale of the Sphinx I will give when I come to my description of Boeotia – and on either side of the helmet are griffins in relief.Plutarch, in his Life of Pericles, gives a little information:
[13.4] His general manager and general overseer was Pheidias, although the several works had great architects and artists besides. Of the Parthenon, for instance, with its cella of a hundred feet in length, Callicrates and Ictinus were the architectsIf you compare this to the hundreds of mentions of the Mausoleum of Halicarnassus, this is quite shocking. What do survive are some works that imitated the Parthenon or depicted the Acropolis, although again very few compared to the number of monuments that imitated the Mausoleum.
The first was the Great Tomb at Lefkadia, shown in this elevation draw by Prof Petsas the excavator.
As is clear from the remains of the painted metopes at Lefkadia, they show that they were copying carved metopes as shadows are painted in, but that those metopes were already quite weathered after having been battered by wind and rain. This is why one of the few ancient references to the Parthenon suggests it had recently been re-painted.
Then in the late Hellenistic period, a small shrine at Eleusis was decorated with miniature versions of the pedimental group depicting the Birth of Athena over the east end of the Parthenon (Athens NM). Eleusis was an important sanctuary to the Athenians, with a major festival ending in a procession there.
A few vases represent the Contest Between Athena and Poseidon shown in the west pediment, but this is disputed by other scholars on the basis that the figures do not match up with what we know of the pediment and that this was a popular Athenian scene (similar arguments can be made for vases showing the Birth of Athena). For example this Athenian vase found in Kertch: drawing and photo (source):
The Madrid Puteal now in the Prado is often cited as evidence for the arrangement in the Birth of Athena pediment:
A similar argument was made for the Ostia Altar (JSTOR). That's pretty much all the evidence we have for the architectural sculptures that decorated the Parthenon in Antiquity.
What we do have are many copies, of greatly varying quality and details, that represented the giant gold and ivory statue which once stood inside, the Athena Parthenos of Pheidias.
We also have two Roman mosaics which depicted the Acropolis in the background, and the Seven Sages in front of it. The better know, and better preserved example was found at Pompeii and is now in Naples.
Another example was found at Sarsina and is now in the villa Albani in Rome:
Both show a schematic representation of the Acropolis, but tell us little about it. More views of the Acropolis, with additional details, can be seen on a series of bronze coins issued in Athens probably under Gallienus.
And that's it folks until the visit of Ciriaco d'Ancona in the 1400s. His description survives, but his drawing do not, only copies by later artists, who clearly didn't get things quite right ...