Where is cigarette lighter fuse located in BMW 118i?

Flip the bonet and there is a black box on the top right hand corner, open that up and there are your fuses. Check in the manual which fuse it is. I believe it to bo 30 or 32 and change it. But often problems are with the actual lighter plug. Try using a phone charger to see if its the unit, if the charger works, its the plug.
Good luck