Errors in wp_db.php

I tried to go to my site at http://www.TellMeAboutThat.com and only got the startup guide for my hosting provider. When I got in touch with Tech Support it was discovered that all my WP files and some other were missing. Fortunately, I had a copy on my PC and was able to put them all back, but some may have been outdated. However, when I attempted to get back in my site I began receiving errors in the wp_db.php file. Most of the had to do with “multisite” which I seem to have corrected one by one by comparing them to similar files I found on line. However, the problem persists. The current error is: “Parse error: syntax error, unexpected T_ELSE, expecting T_FUNCTION in /home/tellmeab/public_html/wp-includes/wp-db.php on line 645”

Can someone help me? I tried copying the file from online after a Google search and that corrected the initial error but everytime I corect one I get another. I’m a rookie at this but follow instructions well. Help!!