It was such a relief to figure out that there is a safe way to make it work again, without losing data. I my case OS was on separate SSD drive, RAID1 was made for user data (2xHDD).
For those with with fresh experience: both former RAID1 members are seen in Windows as regular drives (full access to content), as long as no attempt is made to recreate array in legacy mode (from BIOS). Just follow the procedure as described by Jari ... and you will get safe at home. No stress.