Well, as the title says, this is just to share the default Htaccess file to use or replace, when you run out with errors while trying to work with URL redirects or Trailing Slash Modifications or even Extension Hiding. Once things goes wrong, and it is saved, there is no way to make the site up from the WordPress Admin area, and things can be setup only from the backdoor of the site, i.e from the hosting account only. So, once if you are sure that a corrupted htaccess file is playing the bad game, simply login to the hosting account and replace the htaccess file with the file provided below. I hope that would save you little time finding the htaccess file from the script and uploading it, so i have made the work easier, just download the file below and upload.
Download : Htaccess
Instead here is the code :
# BEGIN WordPress
RewriteCond %REQUEST_FILENAME !-f
RewriteCond %REQUEST_FILENAME !-d
RewriteRule . /index.php [L]
# END WordPress
Copy Paste it to your notepad and save it in htaccessfile format, and simply upload it to the wordpress base diretory, and its Done.