[ubuntu] Installation & Disk Nightmare

I tried to make a fresh install of Ubuntu 16.04 LTE on my hard disk which was part of previous installation with 3 disks (one exteal WD hd). I removed 2 hard disks (old with bad sectors) from PC and left only a new one and exteal HD coected.

I start the installation with USB key and all goes well until the menu where Ubuntu selects the type of installation. I clearly specified to remove old Ubuntu 15.04 and make a fresh installation. The problem is that the installation decided to skip the HD in the PC and starts to format my exteal HD.

1. Major Problem:

My WD exteal disk with all my precious data was probably fast formatted. I stooped the process as soon I saw the program lightning up the exteal HD (two seconds max). Now the disk is unrecognizable in Windows (no letter) but I can see it in HD tools with one UEFI partition in the begiing of the disk and two empty partitions. Please tell me I can get back my data.

2. Problem:

The disk in my PC is not seen by Ubuntu on my USB and nothing can be done to format this disk or fix it. When I run Ubuntu in safe mode it ends up with

/dev/disk/by-uuid/xxxxx-xxx-xxx does not exist. Dropping to a shell!
(initramfs)

I tried boot-repair but the program is giving me only a report option or it is trying to fix the USB drive. Do I have to use windows installation to fix this disk or there is a way to do it with Ubuntu on USB?

Please help me solve this. Thank you.