tu peux commencer par hello, its me (ton nom)
i am calling because i need some help to do a task?
could you help me to do it by sending me a letter or a simple message? i am sorry for disturbing by the way. i suggest you to call me back, so you just explain to me directly how i am supposed to achieve it.
here is my phone number (insère un numéro par exemple le tiens)
call me back as soon as possible and tell me if you can help me about what i said! thank you.
j’espère que ça va t’aider. :)