SSD drive suddenly not accessible, states not migrated due to partial or ambiguous match

Windows, Dell Inspiron. Using an M.2 Kingston Encrypted SSD (SUV500M8240G). Has worked fine until today, when it suddenly stopped being bootable. I booted from a different drive into the laptop's sata port, and using disc manager I can see the M.2 drive as 'unallocated'. When I look under events it states that Device (SCSI etc) was not migrated due to partial or ambiguous match.

Any suggestions would be very gratefully received. I really need to access data on that drive.