I starting my computer and ubuntu loaded without any boot loader. So I searched in internet and the only fix I understand was with the boot repair application.
I suppose this actually meant Ubuntu did not boot?
After installing ubuntu, using something else option and installing it on a different disk than windows 8 ,
That is not a very accurate description of what you did. First your Windows 8 is not on a GPT partitioned drive, which indicates that it couldn't be a typical UEFI installation.
Your Linux swap partition is on the Windows drive, that's not bad, but not very consistent either. The worse thing is that your root filesystem is on an extended partition on the second drive (sdb5). The recommended way is to put at least the root filesystem on a primary partition to have GRUB working properly. With less than 3 primary partitions on sdb, I don't even see a reason to setup an extended partition.
It looks like boot-repair did the best it could by installing GRUB to sda1 (And re-formatting it with EXT4!? Windows doesn't do that. Probably because only EXT3/4 support embedding of GRUB.), where it should have told you to reinstall with a proper partition layout. So I'll do that:
- Please backup all data on sdb and create a primary partition to install Ubuntu there in.
- Choose sdb as target for MBR bootloader installation for GRUB.
- You probably need to repair your Windows bootloader (like oldfred pointed out in his comment) with
bcdboot and reformat sda1.