How do I edit the Post Title after a post?

Only topics have titles, not individual posts. If you've made an awkward typo, you can go find a moderator-- this particular forum has three of 'em, because Apache makes people tired-- and ask him to fix it.

Now then...

How do I block a inactive domain name

Block in what way? Are you getting requests from the domain (referer or putative IP)-- or is it a former domain of your own that some hostfile somewhere thinks you're still using?

btw I'm not sure you're allowed to give that much detail in a post.

:: wandering off to find someone to ask ::

the specifics of your domain and IP don't matter and you can't post them in this forum anyway.

what do you mean by "block an inactive domain"?

Who.is says the domain name is inactive.

Does "inactive" mean "unregistered? Or is it registered, but an "inactive" parked page?

A lot of this junk is coming from .ua, .ru, .cn

Registered, but an "inactive", REFERER spam or .cn domain name rather than a ip.

If you're talking about named domains, then I assume you mean referer spam. Sure, you can block those in mod_rewrite. It will look something like this:

RewriteCond %{HTTP_REFERER} nasty-spam-site\.ua
RewriteRule (\.html|/)$ - [F]

This kind of thing is typically restricted to requests for pages, so constrain the rule to whatever extension(s) you really use. Otherwise your server has to evaluate conditions on every single request all the time everywhere.

Requests from unwanted ranges should be blocked numerically, like

Deny from 12.34

Do not use domain names in "Deny from" directives, as it plays havoc with your logs. (And, presumably, makes your server do extra work beforehand. But it's the log disaster that's most visible.)

Registered domains, but "inactive" appears to becoming a trend for bots/spammers/hackers? At least for me...