Formal:
* Perplexed: This word implies confusion and uncertainty.
* Bewildered: This word suggests a state of being completely baffled and disoriented.
* Puzzled: This word implies a sense of curiosity and a desire to solve the problem.
* Nonplussed: This word emphasizes the feeling of being taken aback and surprised by the difficulty of the situation.
Informal:
* Stuck: This word is simple and straightforward, suggesting a sense of being unable to proceed.
* Baffled: This word is similar to "bewildered" but more informal.
* At a loss: This phrase suggests a lack of understanding and a feeling of helplessness.
* In a pickle: This idiom suggests a difficult situation that is hard to get out of.
Ultimately, the best word to use will depend on the specific situation and the desired tone.