dual boot - Grub not recognizing windows 10

This what i did which made things to mess up.

1)I installed Windows 8.1

2)I installed ubuntu 15.04 in different partition

3)I upgraded windows to windows 10

4)I upgraded ubuntu to ubuntu 15.10

5)Thought to reinstall ubuntu so tried to replace existing ubuntu partition with new ubuntu using usb stick, but when i tried to reintsall using usb it used show an error like:
GNU GRUB Version 2.02~ beta 2-9

Minimal BASH-like line editing is supported. For the first word, TAB
lists possible command completions. Anywhere else TAB lists possible
device or file completions.

grub>_

6)Trying to get rid of this i deleted the ubuntu partition

7)Got stuck in grub rescue mode

8)Now again to set things right i connected a live usb and installed ubuntu

9)Now grub is not recognizing Windows 10

Help me get out of this, I have some important files in windows 10.

For whatever reason (probably due to updating and Windows 10 using a different boot method or something akin to that) the listing of available operating systems has gone missing. This is something that can be fixed in a number of different ways. The simplest one to try is this:

• Open the terminal by pressing CTRL+ALT+T.



• Enter this command:

  
  
  

  sudo update-grub




• Press the ENTER button.




• Enter your password (no asterisks will show, nothing will change on the screen, the cursor will not move, this is normal).


• Press the ENTER button.



• Let the system do its stuff and then enter this command:

  
  
  

  sudo reboot

This will allow grub to automatically find and enumerate the available operating systems and then give you the option to boot to the desired operating system during the boot process.