Problem upgrading to 2.0.4

After i upload and overwrite all the files to my server, my blog totally blankout!

So i checked the instruction, I found i made two mistakes:

1. “As with all WordPress upgrades, the contents of your /wp-content/ folder should remain intact and unchanged.”
–>I also overwrite old files with new ones

2. I didn’t deactivate plugins before upgrading.

Effort has been made to correct problem:
I have tried to delete all the plugins and all other folders not come along with 2.0.4, the problem remains the same.

What should I do now?

I have double checked and made sure that the uploaded files are exactly the same with my hardisk one.

Does it have anything to do with mysql database?