permission denied when logging in

I uploaded wordpress on my domain/blog with hostgator. My
> domain name is
>
> internet-marketing-strategies.com/blog
>
> I then uploaded cognoblue. Everything was working fine yesterday.
> This morning I don’t know why I tried this but I went into my settings and changed the domain to just my domain and not >domain/blog. When I saved changes I received the following error
>
> Warning: require(/home/rebecca/public_html/wp-includes/compat.php)
> [function.require]: failed to open stream: Permission denied in
> /home/rebecca/public_html/wp-settings.php on line 246
>
> When I clicked on “function requred” I received this message
>
> Oops! Looks like the page you’re looking for was moved or never
> existed.
> Make sure you typed the correct URL or followed a valid link.
>
> Please help me fix this. I am trying so hard to get my website up.
>I am a newbie at this and would really appreciate your help.

Thanks,
Judy