If you are having problems opening a file, please share the whole text of the error message. Chances are, you are trying to open a file that was created with a newer version of the software. If that is the case, you will need to ask the person who created the file to export an IDML from it for you.
Yes I'm trying to open a previous file from InDesign but its now appearing that I need to either update Adobe or upgrade my plug ins to the latest version, which I have no idea how to do.
The only option is to get the IDML or upgrade the application. You cannot upgrade to newer plugins.