grub-install: error: cannot find EFI directory

Device          Start        End   Sectors   Size Type
/dev/sda1        2048    1050623   1048576   512M EFI System
/dev/sda2     1050624  837228543 836177920 398.7G Linux filesystem
/dev/sda3  1452748800 1465147391  12398592   5.9G Linux swap
/dev/sda4   837228544 1452748799 615520256 293.5G Microsoft basic data

Partition table entries are not in disk order.


Disk /dev/sdb: 14.6 GiB, 15636364800 bytes, 30539775 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00378159


Device     Boot Start      End  Sectors  Size Id Type
/dev/sdb1  *     2048 30539774 30537727 14.6G  c W95 FAT32 (LBA)

I am kinda lost here. I am not very experienced with ubuntu and might need a little detailed solution. I installed Windows 10 after ubuntu 16.10 and when I try to reinstall grub2 and it gives me the following error: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? Please help!

Try this:

Boot the Ubuntu Live Usb-Dvd.

Open a terminal,

Press Ctrl+Alt+T

Run it:

sudo -i
mount /dev/sda2 /mnt
mount /dev/sda1 /mnt/boot/efi
grub-install --boot-directory=/mnt/boot --bootloader-id=ubuntu  --target=x86_64-efi --efi-directory=/mnt/boot/efi  
reboot