Of course its' OK - I'm grateful for your help. I'll quit now and then post a blank terminal screen to start off again.

TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org


TestDisk is free data recovery software designed to help recover lost
partitions and/or make non-booting disks bootable again when these symptoms
are caused by faulty software, certain types of viruses or human error.
It can also be used to repair some filesystem errors.

Information gathered during TestDisk use can be recorded for later
review. If you choose to create the text file, testdisk.log , it
will contain TestDisk options, technical information and various
outputs; including any folder/file names TestDisk was used to find and
list onscreen.

Use arrow keys to select, then press Enter key:
>[ Create ] Create a new log file
[ Append ] Append information to log file
[ No Log ] Don't record anything

Select "No Log" & press Enter.

TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org

TestDisk is free software, and
comes with ABSOLUTELY NO WARRANTY.

Select a media (use Arrow keys, then press Enter):
>Disk /dev/sda - 500 GB / 465 GiB - HGST HTS545050A7E680
Disk /dev/sdb - 8004 MB / 7634 MiB - Lexar USB Flash Drive








>[Proceed ] [ Quit ]

Note: Disk capacity must be correctly detected for a successful recovery.
If a disk listed above has incorrect size, check HD jumper settings, BIOS
detection, and install the latest OS patches and disk drivers.

Press Enter (disk /dev/sda is already selected, and "Proceed" is the default action)

TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org


Disk /dev/sda - 500 GB / 465 GiB - HGST HTS545050A7E680

Please select the partition table type, press Enter when done.
[Intel ] Intel/PC partition
>[EFI GPT] EFI GPT partition map (Mac i386, some x86_64...)
[Humax ] Humax partition table
[Mac ] Apple partition map
[None ] Non partitioned media
[Sun ] Sun Solaris partition
[XBox ] XBox partition
[Return ] Return to disk selection



Hint: EFI GPT partition table type has been detected.
Note: Do NOT select 'None' for media with only a single partition. It's very
rare for a disk to be 'Non-partitioned'.

Press Enter (EFI GPT partition map is pre-selected)

TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org


Disk /dev/sda - 500 GB / 465 GiB - HGST HTS545050A7E680
CHS 60801 255 63 - sector size=512

>[ Analyse ] Analyse current partition structure and search for lost partitions
[ Advanced ] Filesystem Utils
[ Geometry ] Change disk geometry
[ Options ] Modify options
[ Quit ] Return to disk selection







Note: Correct disk geometry is required for a successful recovery. 'Analyse'
process may give some warnings if it thinks the logical geometry is mismatched.

Select Advanced and press Enter.

TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org

Disk /dev/sda - 500 GB / 465 GiB - CHS 60801 255 63

Partition Start End Size in sectors
> 1 P EFI System 2048 1050623 1048576 [EFI System Partiti
2 P Unknown 1050624 968617983 967567360
3 P Linux Swap 968617984 976771071 8153088












[ Type ] >[Image Creation] [ Quit ]
Create an image

Select 2 (do not press Enter, just use the up/down arrow keys to highlight it).

The choices at the bottom should change so that List becomes one of the options. Use the left/right arrow keys to select List, then press Enter.

This has been the problem. List is not shown as an option:

TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org

Disk /dev/sda - 500 GB / 465 GiB - CHS 60801 255 63

Partition Start End Size in sectors
1 P EFI System 2048 1050623 1048576 [EFI System Partiti
> 2 P Unknown 1050624 968617983 967567360
3 P Linux Swap 968617984 976771071 8153088












[ Type ] >[Image Creation] [ Quit ]
Create an image

Ah, a problem indeed, very possibly linked to the fact that testdisk sees the partition as "unknown" for some reason (it should see it as type "Linux"). My apologies, of course, for doubting you.

This might be indicative of a deeper problem. So, let's analyse the disk and see if that turns up anything.

Press q to return to the previous screen.

Then select Analyse and press Enter.

Apology not necessary

TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org

Disk /dev/sda - 500 GB / 465 GiB - CHS 60801 255 63
Current partition structure:
Partition Start End Size in sectors

1 P EFI System 2048 1050623 1048576 [EFI System Partitio
2 P Unknown 1050624 968617983 967567360
3 P Linux Swap 968617984 976771071 8153088










P=Primary D=Deleted
>[Quick Search] [ Backup ]
Try to locate partition

Press Enter (Quick Search is the default action)

This may take several hours. I have to get my kip anyway (it's almost 4am over here).

Are you able to defer continuing with this until tomorrow morning?

Please don't switch your computer off at any point.