Cannot access shares following disk swaps - URGENT

We have a ReadyNas NV+ RND 4250. I am resident in the UK and the NAS is used for file share / server for my small manufacturing business. I have basic IT literacy, so please go easy on the tech speak

The NAS has had 2 disks in it from new (2008), capacity 465Gb.
I have not been able to access Frontview for a number of years, due to a forgotten password. Therefore we have no back up jobs!

2 weeks ago one of the disks apparently failed. After much messing arround between the two disks I managed to re-boot and get the system up on one disk. I had already ordered two new WD WD1003FBYX RE4 1TB SATAII 7.2k 64MB Enterprise Hard Drives to add to a spare WDC WD5002ABYS which i had but not got working in the NAS. Note all are on the HCL.

Note, I have only been able to access the logs since I reset the firware and password defauly so could access the system using FrontView, which was later on Today!

17 Aug - Having the NAS up on one remaining disk, I inserted one of new 1TB disk to replace the failed 500Gb disk. XRAID added this

The following day, I added the second new 1Tb drive in 3 and the spare 500Gb drive in 4 (at least I think this was the order).
After a number of hours, the disks reported that they were fully redundant and the NAS worked perfectly for two weeks till yesterday.

Yesterday, friday 02 Sept, I was concisous that I still did not have Frontview access to create a proper back up routine so my logic was to remove the disks and try them in the NAS indepently as two pairs both with the same data (where I seem to have gone wrong?). Having read various forum posts it was apparent I would need to reset the firmware to default the password in order to acccess Frontview. The reason for removing the two disks was so I had a backup, if the firmware reset failed (again, probably where I have gone wrong?).
So I powered the system down and removed the original 500Gb disk and the new 500Gb drive, leaving the two new 1Tb disks. Re-booting the NAS did not work

The system restarted, however the system reported the following error: (which remember I have only access today)
"The paths for the shares listed below could not be found. Typically, this occurs when the NAS is unable to access the data volume. Derek Marion media Bill backup BCP Mark"

I then reinserted the two 500Gb drives and still nothing, (the same error message appears in the log).

Bearing in mind at this point I still had no Frontview access to error logs I'm afraid I went on tried various combinations of drives in different bays in a desparate attempt to get my data back online. Unfortunately none of this worked! The last time I tried RAIRar detected one of the disks and started a resync on that disk so I left it running into last night to see if this helped. Again this did not work!

So this morning i tried again and decided I had to try the Firmware reset so at least I could get Frontview and some logs up to find out more. After a couple of attempts being careful to avoid mistakenly doing the "Factory Default" i did finally manage the firmware reset and access Frontview so I have full access to logs since 04 Feb 11. I can send this on if it helps?

So my problem is I whilst I can access the NAS frontview and see the shares I cant access the data keep getting this message
"The paths for the shares listed below could not be found. Typically, this occurs when the NAS is unable to access the data volume. Derek Marion media Bill backup BCP Mark"

The volumes being reported are - I think these are back in the correct order but I'm not sure!
Ch 1 : WDC WD5001ABYS-01YNA0 [465 GB] 463 GB free - 2008 disc that was working
Ch 2 : WDC WD1003FBYX-01Y7B0 [931 GB] 465 GB free - one of two new 1TB drives added 17/18 Aug
Ch 3 : WDC WD1003FBYX-01Y7B0 [931 GB] 928 GB free - one of two new 1TB drives added 17/18 Aug
Ch 4 : WDC WD5002ABYS-02B1B0 [465 GB] 0 MB free - the other new 500GB drive added 18 Aug

Now that I'm in the Frontview and configued a correct e-mail I am also getting another e-mail error:

"The X-RAID engine has failed to start. To ensure data integrity, please refrain from using the NAS and contact Support immediately."

I have downloaded a set of logs and can e-mail / post these if that helps?

I have no backup and am in real big trouble:( if I cant get my data back up. As a small business I really can not afford to loose all my data, so I would really apprecaite your help. Please bear in mind I am no tech expert, as you can probably guess.

I have a suspicion that by swapping around the disks, I have messed up something? How does XRAID cope with being messed around by swapping disks around?

I hope you can help.