Roon uses LeveDB as a a database backend I believe. I’m not looking to become a support contact for this 
but if anyone is DIY inclined there are some tools that offer the hope of leveldb repair. They are of the open source variety and a few tech smarts might be required.
Anyone feeling stuck could WORK ON A COPY and give something like this a go. Thought long and hard before posting but erred on the “it might help someone” side. It’s an at your own risk suggestion…