ERROR 500 – INTERNAL SERVER ERROR

Please ignore the url at the moment. I have directed my domain name to another page at the moment because my WordPress installation is broken and I link to my site on my cv. Hence I am in the process of putting a holding page on there for now.
My domain expired and I realised a few weeks later. I contacted my hosting provider and had it set up again but the next time I tried to use my site I got the message: ERROR 500 – INTERNAL SERVER ERROR.
I followed every tutorial I could find and over the last week I have tried:
Changing plugin names, removing plugins, renaming .htaccess, removing all my wordpress files and adding them again from a back-up and then finally downloading a clean version of wordpress, deleting my database and adding a new one and trying a completely fresh install. I get exactly the same error as soon as I try to log in to my wordpress site. I have cleared my cache and tried different browsers. The only network error is with the wp-login page.