Need help repairing windows 10 on separate drive

[Smoky Mcpot]

Windows 10 became corrupted on my computer and was in an auto repair loop...by this i mean it would try to boot up but fail because of the corruption and would then try to auto repair but fail again due to the corruption and would restart a few seconds after starting auto repair and would just loop like that.
The only way i could get the computer to boot up was to install a separate windows 10 on my D drive and boot it from there but it is just the bare bones operating system and of course the D and C drives have switched places.

Does anybody know how i can repair or reinstall the original os which is now on the d drive without losing any of the data or programs.
Thanks

 

[Colif]

first I would use temporary C drive to copy anything on old C Drive you don't want to lose (Mostly data as programs can be replaced) onto Temporary C drive (what is normally D drive) for now.

Might make it easier to remove data cable from this drive before trying to fix C, will be less confusing later on - unplug PC when you do this.

See if we can get into safe mode on old install
with just the old C installed, boot from the win 10 installer
, on 2nd screen after languages, choose repair this pc, not install
choose troubleshoot
choose advanced
choose start up options
hit the restart button
choose a safe mode (it doesn't matter which) by using number associated with it.
PC will restart and load safe mode

actions are determined by cause. see f its just windows:
right click start button
choose powershell (admin)
type SFC /scannow and press enter
once its completed, type this command into same window:
Repair-WindowsImage -Online -RestoreHealth and press enter
SFC fixes system files, DISM cleans image files, re run SFC if it failed to fix all files and restart PC

if it still happens, boot back in using installer again, follow same steps as above to get to blue menu
choose troubleshoot
choose command prompt
type chkdsk C: /r and press enter - this will check the hdd similar to what auto repair should be doing.

have you been getting any BSOD?

 

[Smoky Mcpot]

first I would use temporary C drive to copy anything on old C Drive you don't want to lose (Mostly data as programs can be replaced) onto Temporary C drive (what is normally D drive) for now.

Might make it easier to remove data cable from this drive before trying to fix C, will be less confusing later on - unplug PC when you do this.

See if we can get into safe mode on old install
with just the old C installed, boot from the win 10 installer
, on 2nd screen after languages, choose repair this pc, not install
choose troubleshoot
choose advanced
choose start up options
hit the restart button
choose a safe mode (it doesn't matter which) by using number associated with it.
PC will restart and load safe mode

actions are determined by cause. see f its just windows:
right click start button
choose powershell (admin)
type SFC /scannow and press enter
once its completed, type this command into same window:
Repair-WindowsImage -Online -RestoreHealth and press enter
SFC fixes system files, DISM cleans image files, re run SFC if it failed to fix all files and restart PC

if it still happens, boot back in using installer again, follow same steps as above to get to blue menu
choose troubleshoot
choose command prompt
type chkdsk C: /r and press enter - this will check the hdd similar to what auto repair should be doing.

have you been getting any BSOD?

Ah sorry I should have updated this as I have got the system back up and running now.
As you said I moved all the important stuff to a separate drive and I had the latest version of windows 10 install software put on an external hard drive then reinstalled win 10 and moved all the backups I made back to the c drive.
I had to reinstall a number of programs but I have almost everything back to normal now.