Renault Clio 2002 radio and interior lights not working. Help?

Hi, my radio and interior lights arent working on my 2002 Clio. i had my friend take a look at the fuses and as he went to put a new one in the blown fuse, it blew it. he tried again, and it blew it again. so he tried a larger fuse which shouldnt have blown and guess what, it blew it. Please help, as we have no idea whats wrong or how to fix it?

Thank you.

Natalie
April 2009