Internal Server Error on Wp-admin page

Hi! I am using wordpress 2.0 (I know :(:( I just did not upgrade!) on my site http://bouncy-bubbles.net

I checked a few days ago everything was fine but today when I tried to access my wordpress admin page ( http://bouncy-bubbles.net/wordpress/wp-admin/ ) to make a new post, I could not. I get this error.

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@bouncy-bubbles.net and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I don’t understand what to do ad I have been quite inactive in the WWW for last few months and I seem to have forgotten everything. Please help me. I have not changed anything in the wordpress folder for a very long time (months)..then why this error coz I could access the admin page a few days ago.

How do I fix this?
I wanted to finally upgrade wordpress and add a new theme but now I cant 🙁 I do not want to lose all my posts and want to be able to access the admin page.

Please help me. Thank you.