Question: When did the modern English alphabet develop?

Modern English



Modern English (sometimes New English or NE[3] as opposed to Middle English and Old English) is the form of the English language spoken since the Great Vowel Shift in England, which began in the late 14th century and was completed in roughly 1550.
With some differences in vocabulary, texts from the early 17th century, such as the works of William Shakespeare and the King James Bible, are considered to be in Modern English, or more specifically, are referred to as using Early Modern English or Elizabethan English. English was adopted in regions around the world, such as North America, the Indian subcontinent, Africa, Australia and New Zealand through colonisation by the British Empire.
Modern English has many dialects spoken in many countries throughout the world, sometimes collectively referred to as the anglosphere. These dialects include American English, Australian English, British English (containing English English, Welsh English and Scottish English), Canadian English, Caribbean English, Hiberno-English, Indian English, Pakistani English, Nigerian English, New Zealand English, Philippine English, Singaporean English,  and South African English.
According to the Ethnologue, there are almost 1 billion speakers of English as a first or second language.[4] English is spoken as a first or a second language in a large number of countries, with the largest number of native speakers being in the United States,  the United Kingdom, Australia, Canada, New Zealand and Ireland; there are also large populations in India, Pakistan, the Philippines and Southern Africa. It "has more non-native speakers than any other language, is more widely dispersed around the world and is used for more purposes than any other language".[5] Its large number of speakers, plus its worldwide presence, have made English a common language ("lingua franca") "of the airlines, of the sea and shipping, of computer technology, of science and indeed of (global) communication generally".[5]
Development
Modern English evolved from Early Modern English which was used from the beginning of the Tudor period until the Interregnum and Restoration in England.[6] The works of William Shakespeare and the King James Bible are considered to be in Modern English, or more specifically, are referred to as using Early Modern English or Elizabethan English. By the late 18th century the British Empire had facilitated the spread of Modern English through its colonies and geopolitical dominance. Commerce, science and technology, diplomacy, art, and formal education all contributed to English becoming the first truly global language. Modern English also facilitated worldwide international communication. English was adopted in North America, India, parts of Africa, Australasia, and many other regions. In the post-colonial period, some of the newly created nations that had multiple indigenous languages opted to continue using Modern English as the official language to avoid the political difficulties inherent in promoting any one indigenous language above the others.[7][8]
Outline of changes
The following is an outline of the major changes in Modern English compared to its previous form (Middle English), and also some major changes in English over the course of the 20th century. Note, however, that these are generalizations, and some of these may not be true for specific dialects:
Morphology
"Like", "same as", and "immediately" are used as conjunctions.[9]
"The" becomes optional before certain combinations of noun phrase and proper name.[9]
Pronouns
Loss of distinction between "whom" and "who" in favor of the latter.[9]
The elevation of singular they to formal registers.[9]
Placement of frequency adverbs before auxiliary verbs.[9]
Verbs
Regularization of English irregular verbs[9]
Revival of the present ("mandative") English subjunctive[9]
Elimination of "shall" to mark the future tense in the first person[9]
Do-support for the verb "have"[9]
Increase in multi-word verbs[9]
Development of auxiliary verbs "wanna", "gonna", "gotta"[9]
Usage of English progressive verbs in certain present perfect and past perfect forms.[9]
Phonology
Up until the American–British split (1600–1725), some major phonological changes in English included:
Initial cluster reductions, like of /ɡn, kn/ into /n/: making homophones of gnat and nat, and not and knot.
The meet–meat merger in most dialects: making the words "meat", "threat" and "great" have three different vowels, although all three words once rhymed.
The foot–strut split: so that "cut" and "put", and "pudding" and "budding" no longer rhyme; and "putt" and "put" are no longer homophones.
The lot–cloth split: the vowel in words like "cloth" and "off" is pronounced with the vowel in "thought", as opposed to the vowel used in "lot".
After the American-British split, further changes to English phonology included:
Non-rhotic (/ɹ/-dropping) accents develop in the English of England, Australasia, and South Africa.
Happy-tensing: final lax [ɪ] becomes tense [i] in words like happY. Absent from some dialects.
Yod-dropping: The elision of /j/ in certain consonant clusters, like those found in "chute", "rude", "blue", "chews", and "Zeus".
Wine–whine merger from the reduction of /hw/ to /w/ in all national standard varieties of English, except Scottish and Irish.
In North American and Australasian English, /t, d/ are flapped or voiced to [ɾ] between vowels.
Cot-caught merger the merger of /ɔ/ and /ɑ/ to /ɑ/ in many dialects of General American.
Syntax
disuse of the T-V distinction (thou, ye). Contemporary Modern English retains only the formal second-person personal pronoun, "you" (ye), used in both formal and informal contexts.
use of auxiliary verbs becomes mandatory in interrogative sentences.
"less", rather than "fewer", is used for countable nouns[9]
For English comparisons, syntactic comparison (more) is preferred to analytic comparison (-er)[9]
Usage of the Saxon genitive ('s) has extended beyond human referents.[9]
Alphabet

Changes in alphabet and spelling were heavily influenced by the advent of printing and continental printing practices. 
The letter thorn (þ), which began to be replaced by th as early as Middle English, finally fell into disuse. In Early Modern English printing thorn was represented with the Latin y, which appeared similar to thorn in blackletter typeface (𝖞). The last vestige of the letter was in ligatures of thorn, ye (thee), yt (that), yu (thou), which were still seen occasionally in the King James Bible of 1611 and in Shakespeare's Folios.
The letters i and j, previously written as a single letter, began to be distinguished; likewise for u and v. This was a common development of the Latin alphabet during this period.
Consequently, Modern English came to use a purely Latin alphabet of 26 letters.
See also

History of the English language
International English
Footnotes




 at Ethnologue