internal errors 500

Can anyone please help me before I give up on WordPress?

I have hosting through Godaddy.com for nearlythebionicwoman.com.

I had a working WordPress.org that I was only having tons of trouble trying to figure out how to get a different theme and plugins. I keep getting errors on that to saying that access has been denied.

Now, somewhere on my dashboard I tried to change the URL to the nearlythebionicwoman.com Versus nearlythebionicwoman.com/wordpress and now it won’t let me even log=in to the …/wordpress due to this error 500. Does anyone know how I can fix it? Change the theme? anything and everything?

Thanks so much.
Christina B