If you're not the administrator of the system, there is nothing you 
(or we) can do. You don't have (direct) access to the Horde 
configuration and won't be able to perform the tasks needed to resolve 
any issue (if there is any).
Yes. See the link you were directed to.
From the page you were directed to:

"You need to talk to whoever actually runs your email account for you. 
This might be your ISP, it might be someone else that you paid for web 
hosting or for your domain name, or it might be your IT 
person/department."

To further clarify this: my admin is a friend, who runs a small 
instance of Horde on his server. He didn't have any problems in his 
address book, so I figured I would report because I am having the 
problem. I did talk with him about it, he did look for any leftovers 
of lost phone numbers in the database, but there is nothing.

You obviously did not read or comprehend my bug report. I am not 
complaining about a service outage from my provider.

What exactly do you need to take this seriously? My admin coming in 
and confirming that he merely updated Horde and this happened? My 
admin making this bug report? I think you are being super dismissive 
without any rational reason.

http://wiki.horde.org/ICantGetMyMail

The admin to my Horde server just updated from Horde 5.1 to 5.2.1. 
After this update, a tremendous number of phone numbers in my 
(default) address book are just... gone. They have been deleted from 
Turba completely, and I see no way to restore them. This is 
*critically* bad and should not ever happen.

I have been using Turba pretty much exclusively in conjunction with 
"CardDAV Sync" for Android, and recently with KDE's Kontact, in case 
that helps.

(If anyone knows how I might get my contact information back, it would 
be very appreciated, but I don't suppose there is a way...)