Is it possible to unblock a domain name?
 

I have been using the domain name for over 8 years. But recently I received a complaint and the registrar immediately blocked my domain name. Of course, I eliminated all the reasons that could lead to the blocking of the domain name. But the registrar still doesn't want to unlock the domain name. What can I do in this case?

You can tell in more detail what kind of complaint was received or what reason for blocking.
I faced a similar situation once. I use Pananames registrar. But the registrar immediately notified me. They were given time to fix the problem. So my domain name was not blocked.

My site has been hacked. Prohibited content was posted there, so the domain was blocked. But I have already eliminated all the reasons for this situation.

So discuss this with your registrar. If not unblocked, then look for another registrar.