Assuming the disk has physically failed or in the process of failing is jumping the gun somewhat.. Plenty of occasions I come across corrupt boot files…There’s several scans and commands you can run from a windows disk that will address this. I’m not saying the disk is healthy but windows MBR getting in a tizzy is just as, if not more likely.
Glad to hear it’s ok now, if a reseat of the power cables and data cables to the drive fixed the issue then that pretty much speaks for itself.
Although I agree with the above.. Take this opportunity to do 3 things.
1.back up any important files
2.run a disk health check of some description
3.obtain windows disk so in future you can use it to boot from and run some file scans and repair commands if needed in future.. the way this works is when booted from dvd (or USB flash drive if your main board supports it) you can scan for example broken /corrupted windows system files, and any found are replaced by a fresh copy from the windows disk.