The adverb 大不了
The adverb 大不了 
has the following two meanings:
1) "at the worst".
In this meaning, it emphasizes that if something goes wrong, a solution can be found.
In a sentence, 大不了 is placed before a predicate, which is expressed by either a verb or a verb phrase.
has the following two meanings:
1) "at the worst".
In this meaning, it emphasizes that if something goes wrong, a solution can be found.
In a sentence, 大不了 is placed before a predicate, which is expressed by either a verb or a verb phrase. Pay attention
A verb phrase is a combination of a verb and an auxiliary word. The auxiliary word can be either an auxiliary verb or an object.
Examples
坐错车没关系，大不了就是坐回去
It's okay to get on the wrong bus. At worst you will come back when the bus turns around
zuò cuò chē méiguānxi, dàbùliǎo jiùshì zuò huíqù
失败了不要紧，大不了从头再来
It doesn't matter if you fail. You can just start all over again
shībài le bú yào jǐn, dàbuliǎo cóngtóu zài lái
2) "serious", "severe".
In this meaning, 大不了 is used in phrases like "it's no big deal", "it doesn't matter".
大不了 can be followed by the particle 的 .
.Examples
别发火，没什么大不了
Don't get angry, it's no big deal
bié fāhuǒ, méishénme dàbuliǎo
这有什么大不了的
What's the big deal?
zhè yǒu shé me dàbuliǎo de