regista_one on "500 error"

I got this error yesterday. The error occured when I tried to connect jetpack with my wp.com account. I tried a WP tutorial on how to solve the issue and renamed htaccess, then renamed the plugins directory to deactivate them, then reloaded wp-admin and wp-instals (what ever the name is) from an other wp install and nothing worked. Then I decided to delete the install and have a fresh one (my site was new anyway). My host provided MOJO installer (what a pain!). It started installing two WP in the same directory out of the blue, so I cancelled the install. I tried to reinstall and it didn't want to connect to my domain anymore. Gave me some error. I said ok, I had enough with MOJO anyway, it gave me some errors before adn ipage recommended me then not to mind them and go on, or to wait 24 hours or something.
Last I uploaded my own WP, configured the wp-config... but same error. What is the problem? what can I do? I am a new user, and really I am frustrated with WP and with ipage and mojo. Why nothing works right?