Unfortunately this is one of those questions we can't answer with any certainty. It could be a fuse or and MCB, but then the question is why have the protection systems tripped, it needs to be traced through to find what has stopped the current reaching the sockets in the caravan, and then the cuase needs to be corrected.
I have to suspect that as you have asked the question, you are not confident with working with electricity, and bearing in mind how lethal 230V ac can be if messed with, I suggests you consider getting professional help from one of the mobile
Approved Workshop Scheme caravan engineers.