how to avoid search string "?" to index in google

i am seeing "?" string is getting indexed in Google search from my site. i am using wordpress. while checking webmaster quality guidelines there are suggestion to avoid/reduce this type of strings via HTACCESS file. but how?

some of my site search pages are in sesults like

domain.com/?=key+word

pleas guide.

 

If Your pages are indexed in google you dont need to change

Otherwise If you would like to change and you are using Wordpress, go to the admin panel and Use Permalinks
codex.wordpress.org/Using_Permalinks

 

thanks for your reply, but i am not asking to reset my permalinks.
i am looking to block crawler access to search pages like domain.com/s?=keyword

 

Make a robots.txt file in the root of the site with such content

User-agent: *
Disallow: /s?=keyword

 

there are about 100s of urls with "?" string. not only one.

 

which permalink structure are you using?

 

/month/date/post

 

I think there is a wordpress plugin or setting you can use to get rid of the ? in the URLs. try searching for it.