Basic sentence: "I have lost my... (camera/keys etc"
我丢失了我的相机 is the formal way to say I lost my camera, whilst 我把相机丢了 or 我把相机弄丢了 is more colloquial. 

There are some differences between 丢失 and 失去. 

丢失 means you lost something. 

失去 means you can not keep something precious(often abstract things, like your love, someone's trust and kindness, etc.) any more because of some reason behind. For example, 你失去了你的爱人，meaning you can not get the hold of your lover. There should be some reason why she left you. It might be she wouldn't love you any more. 

In short, 丢失 means you lost something you don't know where it has gone, whilst 失去 most of time you know where it has gone and also the reason why.