In Japanese, there are several adverbs that are traditionally used exclusively with negative expressions (containing ない). 全然（ぜんぜん）
is one of them. When used at the beginning of a ない (or ません) containing phrase, 全然（ぜんぜん)
has the meaning of ‘completely not (A)’, or ‘not (A) at all’.
Oh shoot, I don't have any toilet paper at all.
I broke up with her because she didn’t help out at all with house chores.
In writing, it is equally as natural to use either 全然（ぜんぜん）
as kanji, or hiragana only, so both forms may be used confidently.
is more flexible (and friendly sounding) in casual conversation than 全（まった）く
, a similar expression which has a formal (often negative) nuance.
I don't have any money this month either, so I am only eating bread.
The souvenir we got from our junior member yesterday was not tasty at all, don't you think?
While both of these sentences have the meaning of ‘not (A) at all’, まったく
could give the listener the impression that you are not pleased with the situation. This will depend quite a bit on tone of voice, though.
Despite originally being used only with negative expressions, it is becoming more and more common for ぜんぜん
to appear with positive expressions as well. In these cases, it just has the meaning of ‘totally (A)’, or ‘completely (A)’.
Although this is technically not grammatically correct, it is becoming so frequently used that it is considered correct by most people (especially the younger generation).