wordpress developer has locked theme?

[Jon the bear]

i have recently taken over as an administrator for a school website which was recently developed (at a ridiculous price by a dreadful developer.) and i am trying to fix the mess we have been left with. the problem is that i have an admin account but cannot change the theme, header, widgets, create templates etc. as they dont appear on the tool bar under appearance. when i change theme it does work but not with this one, i think the developer has locked it somehow and they are being very difficult and not unlocking it without a fight, is there anyway that i could unlock it.