Can you be a songwriter even if you don't know how to play an instrument like piano/guitar?

yess, actually many people that are famous have started out knowing nothing about instruments or how to play them, like Jimmi Hendrix he started out not knowing anything about music, now hes the best guitarist known to man.

being a songwriter does not mean you ahve to perform the songs, many people will sell their songs to popular singers or groups. chances are that most fo the songs your favorite group is famous for are songs written by someone else. of course there are many exceptions and there are groups that do write their own songs too.

Hmmmm kind of. You can only write lyrics, and you won’t have a beginning of understanding into music. Most people will want to hire a songwriter that can at least help write musical score, and know what the rest of the people in the room are talking about. Maybe you could write poems?

ya u can write the lyrics, just not the notes

Before personal computers you kinda’ had to play some piano to compose and arrange music. Well, you can compose on guitar but not as easily. Now computer software can play the music you write so you can compose that way. My piano playing was getting mighty rusty by the time I took my last few music classes. My computer allowed me to hear the music I wrote even though it was too difficult for me to play on the piano.

Yup, you can write the lyrics, someome else can ajust the music for you.

Yes you can as long as you know someone who will write the music for you, or if there is some way you can get music for whatever song you have. But if you need to write the music yourself then of course you need to know something about music.