Expressing “not at all...” with 毫无 and 毫不
Both adverbs have the same meaning, but we should use them a little bit differently.
The adverb 毫无
We use the adverb 毫无 
to emphasize the absolute absence of something.
We should state it before a noun which expresses an abstract concept.
to emphasize the absolute absence of something.
We should state it before a noun which expresses an abstract concept.Examples
他说的话根本毫无意义
What he said made no sense at all
tā shuō de huà gēnběn háowú yìyì
他们毫无理由改变
They have no reason to change
tāmen háowú lǐyóu gǎibiàn
像那样的行为毫无道理
Behavior like that makes no sense at all
xiàng nàyàng de xíngwéi háowú dàoli
The adverb 毫不
We use the adverb 毫不 as well to indicate the complete absence of something.
It is usually stated before a verb or an adjective.
as well to indicate the complete absence of something.
It is usually stated before a verb or an adjective.Examples
他的辞职毫不令人惊讶
His resignation was not a surprise at all
tā de cízhí háobù lìng rén jīngyà
他们毫不尊敬自己的父母
They have zero respect for their parents
tāmen háobù zūnjìng zìjǐ de fùmǔ
他毫不费力地找到了那地方
He had no problem finding the place
tā háobù fèilì de zhǎodào le nà dìfang