Describing "not knowing what to do" (as a response to an unexpected event that happened)?

Is there a good word or a great expression that describes not knowing what to do (as a response to an unexpected event that happened)?

Something uncanny happened, and I do not know what to do.

A raccoon drank my cup of tea on the table (and there was still some tea left in the cup). I do not know what to do.

My mom told me that my father is actually me who will travel back in time later and marry her and then procreate with her. I do not know what to do.

Dr Perhaps called himself perhaps and perhaps not surprisingly it was perhaps his real name. So when Dr Perhaps asked me "Would you perhaps make a guess on what perhaps my real name is?", I do not know what to do.

Mr Loy suggested the word "lost" to be used and I looked it up in the dictionary only to discover that

Lost (of a person) very confused or insecure or in great difficulties: she stood there clutching a drink, feeling completely lost | I'd be lost without her

And that I think it's a bit different from not knowing what to do.

But strangely it has the definition of "not knowing what to do" too. However I think when "lost" is used most people will assume it to be an indication of confusion or insecurity. So thank you Mr Loy but I'm looking for an even greater word or better expression if it ever exists.

Stumped: brought to a standstill, uncertain which way to turn, at your wits' end.

Synonyms are: baffled, perplexed, at a loss, floored (informal), at sea, stymied, nonplussed, flummoxed.

Nonplussed: A state of perplexity, confusion, or bewilderment.

At sea is a great metaphor for being unsettled, drifting, directionless. It is a situation where one is powerless and does not know what to do in a given situation.

You could use dumbfounded in your scenario.

affected with sudden and great wonder or surprise