Dual Boot Help

I have installed zorin os 2 weeks ago with dual boot with windows 10
whenever I boot up, it says
Zorin Os
advanced options for zorin
Windows 10

But today I can't log in windows, its not there anymore,
when I checked my file manager in zorin, i saw my partition of windows is perfectly fine, not formatted, how to fix it

Do you mean it is not now listed in grub menu?

Before doing anything else, back-up your data.

If you have the ZorinOS installation USB stick. Boot that and look for "Boot Repair Disk" (often referred as grub repair here). Run that with default settings and see if that fixes the problem. If it throws up error messages, then report them here, to aid further advice.

You can also download "Boot Repair Disk" from here:


Welcome to the Forum!

Like @zabadabadoo wrote save Your Data before you make something. What You could do then is open the Terminal and type sudo update-grub and this maybe detects windows and add it again to the Grub Menu.