Dropped or have dropped?

"I've dropped" emphasises that the event is recent and its effect is still apparent and relevant. If the speaker doesn't want to emphasise this then he or she may use "I dropped".

I see,thanks a lot) Is it the same about the situation when for example when I lost my phone and a friend of mine looking at my new phone is asking me :where is your old phone? And I'm answering :I lost it. So this means that I don't worry about my loss, I bought a new one and don't regret about it. But if I am answering :I have lost it,does it mean that the phone was valuable for me and I regret

Not exactly

You are more likely to say 'I lost it', placing the loss clearly in the past, if you have bought a new one.

If you say 'I've lost it', there may be some possibility that you will find it.

Anonymous So can I say that in such cases the present perfect is like a red signal button saying :attention, attention please

My understanding of that is that the usage of the present perfect leaves some space for suspension, that there is some, often unsaid, follow-up or, at least, some expectation of that whereas the usage of the past simple 'buries' the exp

Anonymousthe usage of the present perfect leaves some space for suspension, that there is some, often unsaid, follow-up or, at least, some expectation of that

Not really. It's more that the present perfect relates something that began (at least) in the past to the present. If you say "I have lost it,' then you are relating the past losing to the present not-ha