I haven’t had it happen to me for a while now. I used to have a boot repair liveCD that’d always do the trick, but I don’t think that specific distro even exists anymore.

The gist is you’ll want to boot a liveCD and use the liveCD to reinstall GRUB, I’m sure you can find the right incantation to do so online somewhere.

Windows basically never nukes the actual linux install. It DOES like breaking the bootloader though. Which is fixable but still deeply annoying.