I know there are several threads about deleting graves and urns but I couldn't find an exact answer to my question.
I think I accidentally deleted the urn of Michael Bachelor when tearing down the Caliente house (I play meetme2theriver's clean version of Pleasantview so I'm not 100% sure the urn was there in the first place).
I only became aware of the urn's existence when reading a wiki entry on Calientes, so my game has been saved multiple times since deletion.
I have no-unlink-on-delete installed and there's nothing wrong with my game...yet.
Did I mess up my hood for good or is there a chance the mod prevented that?

The urn's there on the cleaned version. If you have nounlinkondelete you'll be fine, although if you're worried you can run it through Mootilda's HoodChecker: http://modthesims.info/download.php?t=456523

Thanks, I'll do that.

If you want the grave manifest in the hood, there's also a method to summon ghost, regenerate the tombstone, etc.

from my understanding, summoning ghosts and regenerating tombstone are separate.
and from my understanding, there are more than 1 of both.

another way to restore the grave marker could be through the lot's files. find the lot either in Program Files directory or through the downloaded file/files. then copy (or extract) it to My Documents directory.

No, don't copy it from program files. It'll mess things up in a similar way to putting an occupied lot into the neighborhood does.

how?
I had not encountered problems from copying lot files.

I had often deleted graves before I knew it was a VBT. My neighbourhood is still going strong 10 years on. I wouldn't worry too much but do install nounlinkondelete.

It'll cause corruption because the lot from Program Files contains older versions of characters and relationships which don't sync up with your current game; so you'll wind up with one-sided memories and the like. It's obviously a lot more serious if you've moved sims in and out than if you've not really done anything to the lot, but it's also, well, pointless - there are much easier and safer ways of regenerating a grave if that's what you want to do.