Como dizer "eu não tenho a menor ideia" em inglês

Sugestão
I don’t have any idea.
I have no idea whatsoever.
I don't have the faintest/slightest/ foggiest idea.

I don’t have the foggiest idea why he called me.
Ref. macmillandictionary

I don't have the faintest/slightest idea what you're talking about.
Ref. merriam-webster

Link relacionado aqui no forum:
Cf. /e-eu-e-que-sei/

Espero ter ajudado

In addition to those ways given in that topic plus the ones above:
Clueless - oftentimes meaning "ignorante sobre um assunto" (não tendo informação alguma sobre, etc (clueless about a situation, about some information, and so on.

I became a local, giving clueless tourists directions and holding conversations in Italian. (source: Linguee)

Hello Narezi!
Para mim soa muito bem quando falo:
Have not the foggiest idea: Used to say that a person has no knowledge about something
A: Where are my shoes?
B: I haven't the foggiest idea

Ref. merriam-webster

Regards!