I understand 怎么 generally means "how".
However, I came across the following translated example:
Nǐ zěnme le ？ Shuōhuà shēnɡyīn zhème xiǎo!
What happened to you? You are speaking in such a low voice!
Why does 你怎么了 mean this? Literally, I understand it as "You (are) how?". Is 样 implied? Like in:
Nǐ zěnme yàng?
Literally: You how is it?, meaning How is it going?
Although the translation seems a bit different.