Subject + 不见了
不见了 (bújiàn le) means "disappeared," "gone," or "missing" and is used to describe something or someone that can no longer be found or seen. It is a very common colloquial expression that combines 不见 (not seen) with the change-of-state particle 了. It can follow a subject directly, as in 画不见了 (the painting is gone).
我的手机不见了,你看到了吗?
Wǒ de shǒujī bújiàn le, nǐ kàndào le ma?
My phone is missing. Have you seen it?
刚才还在桌上的钥匙怎么不见了?
Gāngcái hái zài zhuō shàng de yàoshi zěnme bújiàn le?
How did the keys that were just on the table disappear?
那只小猫突然不见了,大家到处找。
Nà zhī xiǎo māo tūrán bújiàn le, dàjiā dàochù zhǎo.
That little cat suddenly disappeared, and everyone searched everywhere.