Hi. I had a registered Counter-Strike 1.6 server IP adress : 80.72.42.125:27015 and it suddenly became unregistered. In this moment it's registered once again. Is there a possibility to back up ranking from for example 3 days ago ?
I'm looking forward to you answer.

Servers can be deleted in the following cases:

1. Server was automatically removed after extended downtime
2. Server was manually removed by you or any user who has the ability to claim it
3. Server was banned from the site
4. Server was deleted due to minor abuse

It does not appear to be anything regarding 3 or 4.

Unfortunately we are not able to recover deleted statistics.

However, you may be interested in knowing that rank is calculated from the past week of data, so if your server is just as popular, it will be back to where it was. Actually, it will be much higher considering you'd want it back three days and I'm assuming that means its been down for about 3 days.

Regarding to point 3 and 4.
When my server can be banned ? And second question. What kind of abuse do you have in mind ? My server has been DDOS attacked for two days. Could it be a reason ?

Banned - Such as when it is full of fake players
Minor abuse - Such as an admin repeatedly posts inappropriate content or abuses features of the page

Like I said though, I couldn't see it being either of those two options.

It was flooded by fake players. I noticed it in my server's logs that one player was connecting to server hundreds times in 1 second.

However, I already told you it was not one of those two options. You would be able to confirm this by it still having rank and by the fact that you could actually add it.