Give me a suitable topic title and solution pls, dual boot, boot entry (OS)

[AfiAzrael]

Okay I got a very old vostro 1720 ran dual boot windows 7 and windows 10. I decided to use windows 10 only so I formated drive C, where the windows 7 belongs to, end up cannot boot at all. Cant find an option to boot drive D in bios. My friend suggest it could be the boot entry was deleted when I format drive C. Anyone can help?

sorry forum admin I really dunno how to put a suitable title, will update it after anyone gave me.

 

[CountMike]

If you deleted BOOT partition than it will not BOOT from it of course. OS, in this case Windows, dictate drive letter so you will not find D: in the BIOS. Now your best bet is to install W10 in place where W7 was.
Cleanest way would be to delete all the partitions on the HDD during W10 installation and let W10 make and use what it needs.