1. copy the code from this link http://www.bloggersentral.com/2009/12/list-post-titles-in-alphabetical-order.html
2. delete "bloggersentral" write ur blog name
3. go to design>add gadget >basics >(select) HTML/java script gadget.
4. paste the code ( with ur blog name)
5. save
see the picture for help "show all post
for any help see "show all picture" from http://vivekaatp.blogspot.com/2011/07/show-all-posts-in-blog.html