I have add 127.0.0.1 wordpress line into hosts file.
I have managed to fix the 403 error by change the permissions of wamp directory in httpd.conf.Now i am geting 404 error.
If i put localhost in browser it shows the wamp index page and if i wrote wordpress it goes to the correct directory so the virtual hosts are working.
Note that the wamp server path is c:\wamp, the apache path is c:\wamp\bin\apache and phpmyadmin is c:\wamp\apps\phpmyadmin.
without virtual hosts, phpmyadmin url is localhost/phpmyadmin.
Maybe i need to change something in phpmyadmin.conf.
Alias /phpmyadmin "c:/wamp/apps/phpmyadmin3.1.1/"
# to give access to phpmyadmin from outside
# replace the lines
# Order Deny,Allow
# Deny from all
# Allow from 127.0.0.1
# Order Allow,Deny
# Allow from all
Options Indexes FollowSymLinks MultiViews
Deny from all
Allow from 127.0.0.1