grammar - Present Perfect with a definite point in the past

Can present perfect be used in sentences with definite past time when we focus on the present result like

I have forgotten my keys on last Wednesday.
=I still do not have my keys

Answer

No, you can't use the present perfect here. Among other things, the present perfect is used to refer to an action that started in the past and continues to the present. However, the verb in this sentence is "forget." The actual forgetting occurred just once -- last Wednesday -- and does not continue into the present. Therefore, the present perfect doesn't work here. Some possible alternatives that use the present perfect are:

Would you believe it? I've forgotten my keys every Wednesday this year.

I've forgotten my keys on the table! (i.e. this just happened)

I've forgotten my keys here before...

To convey your original idea, you'd probably want to say:

I lost my keys last Wednesday and (I) still haven't found them.