Learn Italian: Il direttore vuole riscrivere la lettera. - The director wants to rewrite the letter.

The prefix ri- acts just like the English "re-", indicating repetition or doing an action again. It attaches directly to the front of the base verb scrivere (to write) without any spaces or hyphens to form riscrivere (to rewrite). It is a highly versatile prefix that you can add to almost any action verb to create a new word.

If I want to say "do again" for a verb starting with a vowel, does the ri- prefix change?

Usually, no. You simply attach ri- directly to the verb, even if it starts with a vowel (for example, riavere for "to have back", or riaprire for "to reopen"). The only exception is if the base verb starts with the letter "i", in which case the two vowels merge into a single "i".

Does riscrivere la lettera mean writing it again from scratch, or just editing it?

It can mean both, exactly like "rewrite" in English! Depending on the context, the director might be heavily editing a poorly written draft, or he might have completely lost the original document and needs to write the whole thing out a second time.

Does il direttore refer to a film director in this sentence?

Probably not. While it translates to "director", direttore is typically used for a business manager, a department head, or a school principal. If you want to talk about a film or stage director, you would use the word regista.