I accidentally formatted a Garmin nüvi 1390 and now its not seen by WebUpdater. When I connect to PC it shows as a flash drive. I tried to format it right with "mkdosfs -I -F 32" same issue

Please help me!

First of all NO PANIC! Do you have any backup of the files before the format?
In reality you do not need Webupdate just the device should have the file GarminDevice.xml and the GUPDATE.GCD
after the format! Thie second contains the firmware and the first the explanations of your devices as a Garmin.
After that you make create the directories and copy the files of the maps as before!

Not any backup. Tried to restore those system files with Recuva, but its not finding any GarminDevice.xml and the GUPDATE.GCD

So we have to find those files on Internet for you first and copy them on your device! You said it is a nuvi1390 with the last firmware?

ATM Im deepscanning with Recuva, waiting to finish than if it will not there, I will use your GarminDevice.xml. Interestig that if I enter in test menu by long pressing on battery icon, in this mode WebUpdater will recognize it, it tells me that there is a firmware update for my device, but when I pres next, it tells me that the upgrade file is corrupt.

The fact that reacts like this is a good sign since seams that your flashed firmware is not corrupted and still running correct! So you may also try to make a backup of your device if you have an sd card!
Do you know your HWID? If not you can find it using G7ToWin
I have sent you PM