Problem with my World.

I understand the server went down over the weekend and am wondering if anyone is experiencing problems with their World since:

A roughly forty by forty area around my Spawn point has become inaccessible - I can't place, break, or interact with blocks.

Hardly any hostile mobs, other than Pillagers, Drowned near ruins, and via spawners, are spawning.

Any suggestions appreciated.

Thank you, Roman, that's sorted the Spawn area.. it was set at '16' when I created the world and I've never touched it, but not had a problem either - I've now set it to '0', saved, and restarted.

Just the issue with hostile mobs to go - I've seen 6 zombies and 2 creepers in three days!