How do I fix the external storage on my PlayStation 4?

I’ve had the external storage for a year, now, and it’s stopped working. My PlayStation 4 says it has 144115.2 TB of storage, but it only has 2 TB. I’ve cleaned the USB, and followed advice from a website like rebuilding the database, but it just hides the games on my external storage and says I can’t format it as an extended storage.

How do I fix the external storage on my PlayStation 4?

and says I can’t format it as an extended storage

This usually means that the drive is dead, as it can't modify the partition table or partitions themselves.

You can try to check if the drive works by completely wiping it via diskpart on Windows. This Seagate KB Article should help.

If the drive does not works on your PS4 after you wipe it on diskpart, then is 100% dead at this point.