大家好，
I have two sentences.
商店里也没有一个面包。
商店里一个面包也没有。
My friend says that both are right, but their meaning may be different. In writing, only the second sentence is used.
Please explain to me why is the first sentence is grammatically incorrect, because my friend might be wrong!
也 has the meanings of "also; besides; either; too"
[商店里也] = [even in the stores]
[商店里也]没有一个面包 = Don't have a single bun [even in the stores]
[一个面包也] = [even a single bun]
商店里[一个面包也]没有。 = Don't have [even a single bun] in the stores
[商店里也] = [In the stores too/ also/ either]
[商店里也]没有面包 = Don't have bread [in the stores neither]
[面包也] = [bread too]
商店里[面包也]没有了 = Don't have [bread neither] in the stores
Note: using the word "too" imply there's other item that has been sold out
商店里也没有一个面包。
商店里一个面包也没有。
The first use of 也 means also and the second one put an emphasis to express surprise.
However, the first sentence sounds stilted. 商店里也没有面包 is natural. It might be because if there isn't any bread at all in the shop then there should not be a piece of it. So 一个 is unnecessary here.
第一家商店一个面包也（都）没有，第二家商店也同样没有。
The first shop didn't even have one loaf of bread, the second shop also the same story.
From these definitions of 也，found here, I would say the first 也 corresponds with 2. 'even' and the second 也 corresponds with 3. 'also'
It is not surprising that even and also are very close:
even: Old English efen "level," also "equal, like; calm, harmonious; equally; quite, fully; namely,"
also: Old English eallswa "just as, even as, as if, so as, likewise,"
Looks like the same is true of 也
副词，表示同样、并行的意思：你去，我也去。 If you go, I'll go too.
在否定句里表示语气的加强：一点儿也不错。not even slightly wrong
在复句中表转折意：
虽然你不说，我也能猜个八九不离十。Although you didn't say, I can also make a good guess.
5.表示容忍或承认某种情况：也罢。whatever
The etymology of 也 is a bit hard to follow, maybe a wash basin, maybe a funnel, maybe a snake.
Maybe Drooze could enlighten us??
EDIT: carried away with word origins as always, I didn't answer the question!
The sentence is not wrong, just strange
商店里也没有一个面包。
The shop doesn't also doesn't have any bread.
This sounds strange, because, where is the other part of 'also'?
商店没有啤酒也没有面包。
The shop doesn't have any beer and also doesn't have any bread.
商店里也没有一个面包。
This is not natural for me, because 一个 is not necessary. It is more natural to say 商店里也没有面包. 也 means "the same as x" here. "x" here can be anything in the context. For example, we are taking a vlog now and do not have bread at home. Then we go to the store but there is no bread either. here home is the "x": the situation at store is the same as home.
Anther example: “地主家也没有余粮” （not only you farmers）even (we) landlords do not have extra food (for the coming winter) as well.
(from movie "The Dream Factory" 1997)
商店里一个面包也没有。
This sentence is correct. 一个x也没有 is a common expression. It cannot be taken apart or reversed order. 一个x can be replaced by some other phrase that has the meaning of very little amount of something, in the form of [一][quantifier][object]. For example “一滴水也没有” “一粒米也没有” “一条缝也没有” “一根毛都没有”。也没有 can also be 都没有. 也 or 都 is emphasis, expressing surprise or anger. So it means "not a single (piece) of something".
So in this second sentence, it is emphasizing that store does not have a single piece of bread, and it is very annoying. There is no comparison to anywhere else.
