Breakdown of Die Datei lässt sich leider nicht wiederherstellen.
nicht
not
leider
unfortunately
sich
oneself / himself / herself / themselves (reflexive pronoun)
der
who, which, that (relative pronoun; die, das)
Questions & Answers about Die Datei lässt sich leider nicht wiederherstellen.
Why does this sentence use lässt sich instead of the passive voice with können and werden?
The phrase sich lassen combined with an infinitive like wiederherstellen is a very common alternative to the passive voice. It expresses possibility, translating to 'can be done' or in this case 'cannot be done'. While you could technically say Die Datei kann nicht wiederhergestellt werden, using lässt sich often sounds more natural and less clunky in everyday German.
Why is the reflexive pronoun sich used here if a file can't act on itself?
That is simply how this specific grammar structure works. The fixed phrase is sich lassen plus an infinitive. Even though the subject Die Datei is an inanimate object, it still acts as the grammatical subject for the verb lassen, so it requires the third-person reflexive pronoun sich to complete the construction.
I see the verb wiederherstellen at the end. Is that a separable verb?
Yes, it is! In a simple present-tense sentence, it would split. For example: Ich stelle die Datei wieder her. However, because the main conjugated verb in this sentence is lässt, the second verb wiederherstellen is pushed to the very end of the sentence in its full, un-split infinitive form.
Why does nicht come after leider and not immediately after the verb lässt?