Posts return 404 error

Solution found here:http://wordpress.org/support/topic/168902?replies=8
APPARENT FIX TO THIS PROBLEM:
Ok, I hadn’t come up with anything through the search words option, but then tried under the “Installation” Forum (hadn’t thought of this before, because I’d thought the installation went alright). The Thread is called, and located at:

“Upgraded to 2.5, now pages don’t display… WTF?”
http://wordpress.org/support/topic/164360?replies=71

I didn’t understand a lot of it, but for those of you who are having this problem, and who like me who have no formal training in, or deep knowledge of computers, here we go…:

THE COMPLETE NEWBIE’S FIX FOR POSTS THAT DON’T LOAD IN WORDPRESS 2.5:

1) Log in;
2) On the “Dashboard”, wander over to your top right, where it says “Settings, Plugins, Users”, and Click on “SETTINGS”;
3) Now wander over the next page to Click on “PERMALINKS” (this will be one of several options probably listed over the title “General Settings”);
4) You should now see the title “Customize Permalink Structure”;
Under this, there will be little buttons beside a list of options;
There are now two options to fix the post/page error:
a) – Click the “DEFAULT” button;
– Click on the “SAVE CHANGES” link near the bottom of the page;
(this will mean that the URL’s/Web addresses of your posts will end in something like “?p=123”); OR
b) – Click on the button of your preferred option (you should see some code pop into the box beside “Custom”;
– THEN Click the button beside “CUSTOM”;
– Now, in the box beside “Custom” and right BEFORE the string of code that’s in there, insert what’s BETWEEN these quotation marks: “index.php?”;
– Click on the “SAVE CHANGES” link near the bottom of the page;
(This will give you an URL/Web address for each of your posts almost the same as your preferred option, but just with “/index.php?/” preceding it).

This seems to work; although there is apparently some fix that you can do that removes the “index.php?”, I must confess I don’t really understand how it’s done; I will leave this thread open a bit longer in case any of you more advanced people wish to explain it (hint: imagine that you are playing with “mechano” sets, whereas I am still playing with “duplo” bricks (“Lego” bricks being too small and fiddly…)).