shut up like a clam

Translations
замкнуться в себе
After the argument, he shut up like a clam and wouldn't talk to anyone.
После ссоры он замкнулся в себе и ни с кем не разговаривал.
Definitions
To become suddenly silent or refuse to speak, often in response to a question or situation, similar to how a clam closes its shell tightly.