Magento XML problem

I'm d开发者_如何学JAVAeveloping my first Magento Theme, but for a testing reason, I had to re-install the entire environment. Obviously first of deleting my previous installation, I've copied the folders of my theme. After reinstallation I've put the theme's folders in theirs right place, but now nothing seems to work.. The system completely ignores my xml files: doesn't load the right stylesheet and the layout changes that I've made previously. Before the re-installation the theme worked well.. The cache is disabled.. some advices?

Delete the contents of the var/cache/ directory.