Hi,
If the drives were in an array other than raid 1, then you need to reassemble the array before you can get any data off them. I could be wrong but I don't think any of those data recovery programs can assemble a broken synology array.
Synology data arrays consists of several physical partitions on each drive. sda5, sdb5, sdc5, ect. then software raid 5 of those partitions, becomes md2. Then on top of raid5 is LVM, which is your volume (volume1).
best bet is to backup the current drives (just in case you mess them up further), and take your time learning and trying stuff. I spent a long time researching trying to learn about how all this works, and I'm still noob. I also got lots of help from someone on Testdisk forums by the name of Remy.
edit: here is partition info from my array of 4 x 2TB disks. These files were created from a Parted Magic live CD. Just figured I'd give you an example of what the partition tables should look like, and what linux sees of a working array. I know this doesn't help you much at the moment, but if and when you get your data back, dump your partition info of working disks. It's good to have backups just incase, which is why I just created them for my disks, since I plan to try to upgrade my array from DSM 4.2 to 5 at some point... and who knows what might happen heh
here's a link on how to dump partition info http://ubuntuforums.org/showthread.php?t=1192598
my partition info for example http://www.datafilehost.com/d/b3e6b016
Fortunately I did not configure any RAID, it is in a standalone state. And I also have a same backup disk with a same capacity(2TB) in a good state, will it help to dump the pation info?