What it does now
Like is one of the busiest short words in English. As a verb it means to enjoy or to be fond of, and online it also means to register approval with a tap. As an adjective, preposition, adverb, and conjunction it marks resemblance or manner: a like mind, something like rain, to talk like a lawyer. In conversation it can hedge, approximate, or introduce reported speech or thought. Those jobs share a spelling. They do not share a single Old English ancestor.
Two inheritances, one spelling
The origin of the word like is a native pair, not a loan from French or Latin.
The resemblance family comes from Old English ġelīc, similar or equal, and the adverb ġelīċe, in the same manner. Middle English shortened the prefixed form, so scribes wrote lik, lyk, lich, and like. The Oxford English Dictionary treats the modern adjective as mixed: a reduced native form related to older ylike, and also influence from early Scandinavian líkr and glíkr. That northern contact may be why everyday English did not keep a lich-shaped spelling for this adjective.
From the adjective, English formed a preposition around 1200 and an adverb around 1300. A conjunction appears in the early sixteenth century, cut down from phrases such as like as and like unto. A noun for a similar thing is already late Old English; an equal or match is recorded about 1300; the like and the likes of belong to the sixteenth and seventeenth centuries.
The verb is a different Old English word, līcian, meaning to please, be pleasing, or be sufficient. It is inherited from Proto-Germanic *līkāną. Related verbs include Old Norse lika, Gothic leikan, Dutch lijken, and Norwegian like. Dictionaries place first English use in the Old English period, before 1150, the same broad era as the adjective.
Body, form, and a suffix still in use
Both branches rest on a Germanic root *lik- for body, form, or sameness of form. The adjective is a compound of *ga-, with or together, and that root, reconstructed as Proto-Germanic *galīkaz: having a corresponding body. The structure is comparable to Latin conform, which is an analogy, not a source.
The body noun survived in Old English līc, later lich, a corpse, and in lych-gate, the roofed churchyard entrance where a body was set down before burial. Dutch gelijk and German gleich keep the prefixed equal or alike adjective; German Leiche keeps the corpse noun. English alike is the relative that did not lose its prefix.
The adverb ending -ly belongs here too. Old English -līc and -līce meant having the form or manner of a thing. Germanic built manner adverbs from a word for body or shape; that is genuine morphology, not a later guess.
Beyond Germanic the trail thins. Some handbooks propose an Indo-European root connected with likeness or image; others stop at the Germanic evidence. The deeper history of the body noun itself is obscure, and it is better left unmarked than forced into a tidy family tree.
How the verb turned around
The verb’s syntax is the main change in meaning that still surprises readers of older texts. For a long time the pleasing thing could be the grammatical subject and the person the one affected: a piece of music might like you, in the sense that it pleased you. The modern pattern, with the person as subject, is visible from the late fourteenth century. The older please construction did not vanish overnight.
School histories sometimes describe a clean flip from please to enjoy. Specialists who have worked through Old English examples argue that both a causative reading and a receptive one already existed, so later English mainly let one frame dominate. A further guess, that the verb began as be of like form, then be suitable, then please, is plausible and remains uncertain.
Other remnants of older grammar are smaller. Comparatives liker and likest lasted into the seventeenth century. Southern American like to in the sense almost comes from was like to or had like to, was likely. Feel like, be in the mood for, is recorded in American English from 1863.
Later speech, a new countable, and a fossil
Spoken filler at the end of a clause is attested from 1778. Commentators in the nineteenth century already noticed discourse uses, and they turn up in early colonial New Zealand English. They are not a late-twentieth-century invention. What is recent is quotative be like, the construction that introduces performed speech or thought. Corpus searches do not find it before the 1980s; linguists treat it as a grammaticalization of older manner and reportative uses of the resemblance word, not as a new root.
The clickable noun a like, and the verb of marking a post, extends the enjoyment sense into a countable token. A like control appeared on FriendFeed in 2007; Facebook launched its button in February 2009. New technology, same verb.
If you want one hard fossil, look at -ly beside lych-gate. The suffix still means, historically, in such-and-such a form; the gate still names a body. The two likes on the modern page grew from that same Germanic idea of matching form, then split into resemblance and pleasure, then met again in spelling.