Thread:Sannse/@comment-24574753-20140313220809/@comment-1330470-20140313224744

The best solution is always to ask the user to promote you to administrator. If you know them in real life that might be easy.

There is a process for users to attain administrator rights on wikis with no active admins, see Help:Adoption. I'd recommend you ask the person first and then file a request.