A seller cannot close their account after a transaction, but eBay can and they don't do it lightly, it must have been a serious misconduct of their selling regulations, perhaps selling fake Ps5's ?
In the long run, it looks like eBay saved you some grief here!
If the seller is no longer a ' registered user' you do need to contact Customer Services for them to open a case for you for your refund, or they may just refund you straight away.
I strongly recommend contacting CS 8 a.m. on a weekday when the lines open for ' live agents' as then, there's more chance of Dublin answering.
This is the easiest and quickest way to contact eBay Customer Services, for a Call Back option.
https://www.ebay.co.uk/help/eua?id=5190
Lines open 8 a.m. - 10 p.m. on weekdays
9 a.m. - 6 p.m. on weekends.
Automated agents will be available on chat outside of the above hours.
@bikerwoody1967