Please try the following fix and see if that helps you:
Now, something that was not detailed in that link, so here are the steps to be executed::
1. If you don’t have a restore media or system disk to perform a recovery download Windows 10 from:
This will only download a simple tool which you can use later to create a USB or DVD image with Windows 10 which you can use later to perform the recovery.
2. Restart PC with the USB/DVD, selected advanced recovery options and then open administrative Command Prompt.
3. All you need to do is enter following command :
Substitute C with your system root drive letter in the above mentioned command. This command allows to copy BCDboot file from existing Windows partition to motherboard partition and creates the BCD store in the same partition.
Hope this helps.
I have an Inspiron model 7720. I have 2 hard drives according to my diagnostics test. How do I find out the system root drive letter?
Are the drives set up as two separate ones, or is this a RAID 0 array?
F2 at powerup to check.
Removing the drive is easy to do on this model - however -- if they're in a RAID 0 array, recovering your data will be a much more complex (and far less certain in outcome) project.
If there are two separate drives, remove the primary one and mount it externally - and attach to a working system. Copy your data.
The procedure for removing a drive is detailed here - and is easy on this model.