If you were at the door and found out that you had forgotten your keys you might say: "I have forgotten my keys" ..
but what would it mean if you said I forgot my keys instead?
If you were at the door and found out that you had forgotten your keys you might say: "I have forgotten my keys" ..
but what would it mean if you said I forgot my keys instead?
If you are talking about "the recent past," it would mean you were speaking American English and not British English. For a situation (or, in a context) such as this, BrE prefers the present perfect and deprecates the simple past, while AmE can go either way but the simple past is probably most natural.
See Use of the Present Perfect in Differences Between American and British English. I suppose it's only fortuitous that they use as an example a sentence about losing one's keys.
Another situation, from The English Verb by Palmer is the situation where a family is (American English) or are (British English) preparing to have dinner, and the child reports whether his hands are clean.
In British English the child will report:
Yes, I've just washed them.
while
in a American English, the response is more likely to be, or at least just as likely,
I just washed them.
This blog post on the present perfect on separated by a common language is well written, despite the author being a linguist. :) It's one I highly recommend. It goes into the nuances of what the present perfect expresses that the simple past does not, usually.