In the case that Windows removed the boot entry of your Linux OS, follow these steps.

If your disk is encrypted, decrypt and mount the disk with

sudo cryptsetup luksOpen /dev/sda3 cryptdata
sudo mount /dev/mapper/data-root /mnt

Otherwise, mount your unencrypted disk with

sudo mount /dev/sda3 /mnt

Then, mount the EFI system partition

sudo mount /dev/sda1 /mnt/boot/efi

Continue with

for i in dev dev/pts proc sys run; do sudo mount -B /$i /mnt/$i; done
sudo chroot /mnt
apt install --reinstall linux-image-generic linux-headers-generic
update-initramfs -c -k all
sudo bootctl --path=/mnt/boot/efi install