MacBook won't let me print double sided

Okay so i'm starting to get really angry about this. I need to print something for school and it won't let me do it double sided. Ive tried every option available and it won't work. Ive gone to system preferences and tried to change it. Ive gone to option and supplies and this 'duplex' button doesn't even exist for me. Ive tried going to layout on Word and enabling double sides printing but it won't even let me change it, its permanently turned off. Ive been at this for 2 days and nothing it working. Ive tried every article, youtube video and have asked countless people for help. If someone recommends me a way I've already used i'm going to be angry because I've told about 30 people about the same way not working.