i have back up the database .if i unistall and re-install wordpress.after re-installing wordpress if i upload database then will my content be replaced to my blog?or do i have back up content separately?
You should back up your database separately. http://codex.wordpress.org/Backing_Up_Your_Database http://codex.wordpress.org/Restoring_Your_Database_From_Backup Alternatively, if you click Tools -> Export, you can dump the posts, comments, categories and tags. Then re-install Wordpress fresh. And use Tools -> Import to re-import the data.