Wordpress Login (wp-admin page redirect 404 page (maybe because of .htaccess problem)

My Wordpress blog was running since a long time. And Everything was working right.
The problem started 2 days ago. Something happened with .htaccess file.

And now, my home page is working as usually, but when i try to go on page or a post, nothings work.

I got a 404 error with this message:

'The requested URL /my-page-or-post/ was not found on this server.

Same error page comes when i even try to login to my wordpress admin page (/wp-admin).

If i delete the .htaccess file, i can access admin page and home page but not individual posts pages.

the post pages and homepage start working fine after i put .htaccess file back but admin page access is gone.

heres my .htaccess file

RewriteEngine on
# -FrontPage-

IndexIgnore .htaccess */.??* *~ *# */HEADER* */README* */_vti*

<Limit GET POST>
order deny,allow
deny from all
allow from all
</Limit>
<Limit PUT DELETE>
order deny,allow
deny from all
</Limit>
AuthName avinashtech.com
AuthUserFile /home/avinasht/public_html/_vti_pvt/service.pwd
AuthGroupFile /home/avinasht/public_html/_vti_pvt/service.grp

# BEGIN WPSuperCache
<IfModule mod_rewrite.c>
RewriteBase /
AddDefaultCharset UTF-8
RewriteCond %{REQUEST_URI} !^.*[^/]$
RewriteCond %{REQUEST_URI} !^.*//.*$
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{QUERY_STRING} !.*=.*
RewriteCond %{HTTP:Cookie} !^.*(comment_author_|wordpress|wp-postpass_).*$
RewriteCond %{HTTP:Accept-Encoding} gzip
RewriteCond %{DOCUMENT_ROOT}/wp-content/cache/supercache/%{HTTP_HOST}/$1/index.html.gz -f
RewriteRule ^(.*) /wp-content/cache/supercache/%{HTTP_HOST}/$1/index.html.gz [L]

RewriteCond %{REQUEST_URI} !^.*[^/]$
RewriteCond %{REQUEST_URI} !^.*//.*$
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{QUERY_STRING} !.*=.*
RewriteCond %{HTTP:Cookie} !^.*(comment_author_|wordpress|wp-postpass_).*$
RewriteCond %{DOCUMENT_ROOT}/wp-content/cache/supercache/%{HTTP_HOST}/$1/index.html -f
RewriteRule ^(.*) /wp-content/cache/supercache/%{HTTP_HOST}/$1/index.html [L]
</IfModule>

# END WPSuperCache

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress
RewriteCond %{HTTP_REFERER} !^http://avinashtech.com/.*$      [NC]
RewriteCond %{HTTP_REFERER} !^http://avinashtech.com$      [NC]
RewriteCond %{HTTP_REFERER} !^http://www.avinashtech.com/.*$      [NC]
RewriteCond %{HTTP_REFERER} !^http://www.avinashtech.com$      [NC]
RewriteRule .*\.(.*)$ - [F,NC]

Code (markup):

I don't know what to do...
Anyone can help me please ?

 

no one got a clue?