Fuel cap won't open properly

On most cars there is an emergency fuel flap release , usually behind the boot trim on that side . I cant be more specific as they vary from car to car . What often happens is the release actuator / mechanism tends to stick . You can often rectify by giving a good soaking of WD40 once you get access . Worse case scenario you would need a new flap motor . If you try a little pressure and gently help the flap you may release the flap

Thanks will try that ?