It is by context. Dropped is the main meaning. Lost is the colloquial meaning. It is not possible to differentiate with certainty in this sentence.
I want to add to this that you can make it unequivocal by adding "bort" after "tappat" to say that you've lost it, like so: "Jag har tappat bort min racket". Or you can say that something is lost by switching the order of the words and join them, as in "Min (mitt?) racket är borttappad". Not sure if I'm explaining this well, so sorry if I'm just making it more confusing :P
That's right! You can say either Mitt racket är borttappat or Min racket är borttappad.
Dropped can also be as you know where but in an unreachable place. Lost is more that you have no idea where
Thank you very much! It is over and over an interesting language.
And sorry for 2 questions, but the Android app does not support "editing".
That's another accepted answer. SAOL [the standard spelling dictionary] actually only lists en racket, which is why min racket is the default answer, but we accept both anyway since we know that ett racket is also very common.