have no clue 不知道，没有线索，毫无头绪
 

【例句】
My birthday is later next week. I wish to make it special but have no clue how.
我下周就过生日了，我想要让这个生日特别一些，但是毫无头绪，不知道怎么做。
 

We have no clue as to where she went after she left home.
我们对她离家后去往何处毫无线索。