This error is strange

I have done all this, but still not able to get rid of this bad error
Is there any other way to get rid of this ?
I am planning of deleting everything from my public_html folder and then reuploading all the files from freshly downloaded 4.2.2 version of vbulletin.
And then installing fresh vbulletin by going to
www.forum.com/install/install.php
And then giving old database username and password to the new config.php file.
I know that i will loose all my plugins and custom styles and all, but all my members, threads, my paying subscribers who pay me yearly for vip membership will be still there. Am i right ? Correct me please if i am wrong.