I saw a discussion on SLUniverse about a number of regions closing without notice. The discussion centers on the closing of Beach Front. See: Beach Front Realty Closed?
It seems the land owners collected the month’s tier from tenants and then closed the regions. Correspondence with Linden Lab revealed the closing was ‘deliberate’. I suppose that means the region owner contacted the Lab and scheduled the closing. Not having seen the actual correspondence I cannot tell if the phrasing is nuanced spin that might indicate the Lab closed the owners regions for some reason.
The tenants may be able to get their money back via PayPal. The Lab generally considers these things a resident-to-resident matter and stays out of them.