I don't know what should I do?和I don't know what I should do?有什么不同?哪个正确?

I don't know what should I do?和I don't know what I should do?有什么不同?哪个正确?
I don't know what should I do?和I don't know what I should do?有什么不同?哪个正确?

I don't know what should I do?和I don't know what I should do?有什么不同?哪个正确?
I don't know what I should do.正确.
what引导宾语从句,从句要用陈述语序.

这个叫定语从句
后面要用陈述语序
I don't know what I should do? 正确

第二个对，是宾语从句，要用陈述语序。

后者是正确的。因为，I don't know引导一个宾语从句，在宾语从句中，句子需使用陈述句语序，而不是疑问句语序