* Muffleto: This charm silences someone for a short period of time.
* Silencio: A stronger spell that permanently silences the target until the spell is reversed.
* Imperio: This spell compels someone to do the caster's bidding, which could include preventing them from speaking.
* Confundus: This spell causes confusion and disorientation, potentially leading to the inability to form words or speak coherently.
It's also possible that the character is experiencing some kind of magical ailment or side effect that causes temporary speechlessness, rather than a specific curse.
If you have a specific scene or situation in mind, please provide more context and I may be able to provide a more accurate answer.