If you suspect your .htaccess may be corrupt on your wordpress site, you can try backing up your .htaccess file, and then replace it with this.
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
The above is the default wordpress .htaccess file. And should help to troubleshoot if anything in your own is wrong.