Whatever you do, do not write anything to the disks, and certainly do not
format them !
If all the disks have become unrecognizable at once, my first guess would be that
the Mediasonic enclosure is broken. Your only hope is that while breaking down
it did not destroy the disks.
For lack of information about your computer, here is the general
direction I would have tried in your case.
Try to take out one of the disks and set it up on another computer, or in another
enclosure on the same computer,
to see if it comes up as formatted or not. If the disk is accessible,
make a disk image of it and repeat for the other disks.
If all the disks are saved, try getting the enclosure replaced,
if still under warranty.
Otherwise, mount the images as virtual disks, trying out one or more
RAID recovery products on these virtual drives.
Here are some products I found on google, but more can be found.
Some of them are commercial with trial, which at least will tell you
whether the RAID is recoverable.
ReclaiMe Free RAID Recovery software (Windows freeware, verified as virus-free on VirusTotal)
Yodot RAID Data Recovery ($39.95)
EaseUS Data Recovery Wizard Professional ($69.95)
iCare Data Recovery ($69.99)
If you wish to do it yourself, here is how one person managed it.
The programs he wrote for the recovery can be downloaded from the article:
How to recover from a broken RAID5.
If the disks are unreadable, the situation is not good.
You might need to use professional services, and these are costly.