Additional photo

Your binding up picture looked pretty good, Reem. Provided that you did this quickly after the break occured and that the wound had not dried out then it stands a pretty good chance of healing.
If the wound was 'fresh' looking and moist when you found it then the break had only just occured and was whilst the Acer was in your care. If the wound was dry and hard looking then it happened at the nursery or during carriage and you might want to try for a replacement.

I agree with bulbaholic. if the branch then dies you will need to cut it off. as flush to the stem as you can without tearing any more bark. you can buy a wound sealant to prevent the entry of microbes. lets hop the wound is fresh and it will heal.

Thanks for the replies, the wound did look fresh. Will try and get hold of some wound sealant.
Keeping fingers crossed it will be ok.