“Upgraded” and now I have only a blank screen

Well I’ve been happily using my old 2.3 WordPress for ages but since it kept nagging me to upgrade I decided to bite the bullet and do the upgrade.

Downloaded, unzipped and replaced the directories I was supposed to replace (according to the quick & easy upgrade instructions). Went to my site to see the wonders of Version 3.

But I only get a blank screen. It killed my site.

Nothing, nada. Just the blank screen

What do I do now?

(I’m a enthusiastic amateur and don’t know much about any programming, so answers will have to be of the kind that a blonde can understand even though I am a brunette)

Thanks…