Moca4444,
Well, it depends on how you configured the volumes on the disks.
Try to mount the filesystems that should be there and see if you get any errors. If you can mount them try to save off that data or copy it to another disk.
Does any of your data exist only on one of the disks that are left?
If you have any filesystems that only reside on one disk. then you should be able to retreive that data. Any data that was spread over to the failed disk will be unrecoverable.
What OS are you running? What type of backup product are you using?
If you can't retrieve some data from the two remaining disks, you may have to go back to 2 weeks ago to your last backup and try to come forward to today some other way.