Can an M.2 NVMe SSD degrade after sitting unused for two years?

The SSD itself probably hasn’t been harmed simply by sitting unused. The bigger concern is whether some stored data has degraded, since NAND cells slowly lose their charge when unpowered. Two years at normal room temperature is not an automatic failure, especially for a modern TLC drive, but you should treat important files cautiously and make a backup before relying on them.

There’s no need to replace the SSD just because it was stored for two years. Many drives remain perfectly usable after sitting disconnected for that long. Once it’s running again, install an appropriate firmware update if one is available, keep normal backups, and monitor its health. Long-term cold storage is better handled with multiple copies and periodic verification instead of relying on one SSD.

Retention varies with flash type, temperature, drive age, and how much wear the cells have experienced. Higher temperatures and heavily worn flash can lose data sooner, while a lightly used TLC drive stored at room temperature has a better outlook. Claims that every hard drive or SSD must stay powered on to remain healthy are overstated; power cycling is not a substitute for backups.

Power the system on and check the drive’s SMART or health data with a reputable utility. Look for critical warnings, media errors, percentage used, and available spare capacity, then run the manufacturer’s diagnostic tests if available. If the data matters, copy it somewhere else first rather than starting with repair or recovery software.