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First you should tell the version you are using in your first post.
Most people are using version 2 now.
If you created a templates_c folder delete it that is for version 2.0.x
Also do you have a backup of the working database?
If not that should be the first thing you do when this is fixed.
O.K. now try going into your database and find the user table (yourxoopsprefix_user) then look for the name of the theme in quotations 'redstar' or whatever you changed it to, and change it back to 'bluely' you may have to do it to all your users. (easy with the replace option in your text editor) not sure if there is somewhere else that might have an area to change the default theme in the database, I didn't see any with a quick look through.
Someone else that remembers version 1.3.x might have more info.
The above procedure might work. If not
Maybe time to upgrade to 2.0.5.2
I just upgraded my last 1.3.x site to 2.0.5.2 and it went smooth. But post here before an upgrade.
Again most people answering your post are thinking of version 2 so don't create any new folders or files.
The problem is most likely the theme.