As you'll find in the course of your Chinese study, there are many different combinations to express the same idea. That's the beauty of Chinese characters. In regards to your question, however. To lose, in the meaning of being unable to find something is most often rendered thus: 丢diu1 我的钥匙丢了。I've the lost the keys. You can also use the 把 structure: 我把你送给我的那本书弄丢了。I've lost that book you gave me. Here, 弄nong4 is a general verb meaning "to do" and 丢diu4 serves as its verbal complement. Someone who often loses or misplaces things is called a 丢三落四。diu4san3la4si4 Cannot find is, of course, 找不到 zhao4bu2dao4 and is often a good translation. There's also 丢失. (used for concrete objects) To lose, as in its sense of being deprived of something is often rendered así: 失去 shi1qu4 我不想失去你。I don't want to lose you. 失去自信／知觉 To lose self-confidence/consciousness. There's also 丧失。sang4shi1 (used for abstract objects) To lose one's job, or, to become unemployed has a set phrase: 失业 shi1ye4 丢掉 diu1diao4 can also be used。 eg: 出了重大事故，把工作给丢掉了 There was a huge accident that lost (whomever) their jobs. (This is a passive sentence in Chinese, so the 给3 reinforces the passiveness) The Chinese characters are often like pieces of puzzle that can be switched around seemingly willy-nilly to form many combinations that, for the most part, are of the same meaning but with slight connotative differences. Looking up even a simple verb such as "to lose" will get you many combinations, but don't feel overwhelmed by the whole array of options because in reality oftentimes the differences are negligible and only at a relative high level should you even begin to worry about teasing out the subleties!

I lost sth. → 我丢了... wo3 diu1 le... e.g. I lost my wallet. → 我丢了钱包。wo3 diu1 le qian2 bao1. Note: In Chinese, the passive voice would be more frequently/normally used in this situation. For example: 我的钱包丢了。 Literally means "My wallet (is) lost". *wo3 de qian2 bao1 diu1 le.

I lost my wallet (as Daniel said).I have lost my wallet I've lost my mind, dog, handbag.