If the htaccess file is in place, but the rules are not being activated you will need to ask your server admin, you may need some server specific line in htaccess to make it work. Tell them your .htaccess is not working, I am not familiar with your environment so I am not sure what it could be, there is nothing special about our default .htaccess file, it should just work.
You might also search the forum here for htacces, I seem to recall someone else years ago at 1and1 or godaady or some other bad host had to add something extra to make it work.