The is usually a fuse inside the black control box that contains the 'board' that runs your fridge. This is located on the outside of he fridge, thru the exterior door. It should be on the left side of the back of the refer.
If this fuse is NOT blown, then you might have a control board (lower board) or eyebrow (upper board) issue and you should have an authorized Dometic service center check it out for you.
There is always the possibility that your cooling unit is shot, which is not a difficult replacement, but one that again, should be done by someone who knows what they are doing.
A proper diagnosis here is critical.