26? That's modern history. But ancient history up to even the 17 century English had 27 letters. The 27th, the last letter wasn't z, it was et or &, the ampersand, which meant "and." It used to be letter. It's a lot like Pluto being dethroned, demoted as a planet. Now, the English dictatorship of writing won't even allow it as a word or letter.
Real question though is how was it pronounced? It started out as the combination of e and t, then slowly evolved into an 8 like character finalizing as &. Like watching a lion, king of the beasts, devolve into a vestigal house pussy cat with no bite left A cat that even the mice no longer fear.
Meanwhile Greek has 27 letters, most translate to the English letters. Although Muslims liked that C letter instead of the Greek, alpha beta, gamma beginning trio. One Greek letter for each book of the New Testament Bible.
Sounds are a combination of letters. You can't pronounce a word or syllable without at least one vowel. There are no English words without at least one vowel. a, e, i, o, u and sometimes y. they have more than one sound, long and short a, like fare or father. i can sound like dime or dim, different sounds. o like loan or Lonnie. e like cream or den. u like dumb or use. oo is like u, doom. That's sounds = over double the number of vowels. Th can be like teeth or these, different th sounds.
Every language also borrows words from other languages, bringing even more sounds with them, for the same letters. English in New York, Boston and Alabama have very different sounds for the very same letters or words. Grease has an s sound for most states. In the Deep South Grease has a z sound for the s. In fact expert linguists can tell which states you've lived in, just by hearing you pronounce a list of about 20 English words. You mimic the people around you, changing your pronunciation to fit more closely those you're near. It almost caused a major international problem when Bill Clinton pronounced "Kosovo" in former Yugoslavia, as it seemed to imply he was siding with one side over the other.