Hello everyone.
I am writing to inform you that i found a way to work around the problem.
Reading everything i found on the net, i managed to restore all my data.
I think that this means that the card is not actually corrupt.
The procedure is as follows:
1. DO NOT DO ANYTHING ON THE PHONE! Do not factory reset, do not erase, do not format. If this happens, no restoration can be done, as the key to decrypting the card is lost.
2. Connect the corrupr card to a windows or linux pc. It will not be able to read it probably, because it is decrypted. It will only show the existence of two particions.
3. Use a cloning tool to make a clone of the card. I used WinImage. It doesn't matter that you don't see anything in the card. Datta is there, but it is decrypted and therefore can't be read by anything but the phone.
4. After opening Win Image, go to Disk/Create Virtual hard Disk Image from Physical Drive (reads all card data as raw in a .vhd file).
5. Take another card with the same storage capacity as the corrupt one.
6. Connect the new card to your pc and again using Win Image, go to Disk/Restore Virtual Hard Disk Image on Physical Drive. This will copy the clone of the card to the new one. In my case i had a SunDisk 16Gb card and i bought a Transcend 16Gb card. It worked perfectly, despite the difference in the brand.
7. Insert the new card to your phone and everything is there. All of my photos, videos and apps. My phone recognized the missing/corrupt SanDisk 16 Gb external card, as internal storage.
8. Back everything up, and buy a phone with more internal storage next time.
That's what i've learned.
The whole "set sd card as internal" thing is at beta stage i thing...but with a phone with 8Gb of internal storage it seemed a good idea. But sd cards are not intended for such a use.
Hope all this was helpfull.
Regards, Leonidas.