"The man does not find his trousers."
Translation:Người đàn ông không tìm thấy quần của mình.
When paired together it's more emphatic. It can also be used to signify a past action (as it means "seen") like:
Tôi không tìm = I don't/won't find (it)
Tôi không tìm thấy = I didn't find (it)
Của mình sounds so weird in this sentence! Am I the only one who translate it to 'us' when I read this sentence? This is coming from someone who has been speaking Vietnamese their whole life but can't read and write.
Is it also possible to say tìm không thấy here? In the sense of searches but doesn't find (which is the usual intended meaning).
Definitely. Here's a mouthful: "Tôi cứ tìm mãi mà không thấy chìa khoá nhà ở đâu cả" = I kept searching/looking but couldn't find the house key(s) anywhere at all.
Yes; "Tôi tìm hoài mà tìm không thấy." = "I kept searching but couldn't find (it)."