RAID configuration data is stored in the controller and on the drives. This data includes the size of each drive, the number of drives, it's physical location (port #) on the motherboard and the type of array (RAID5) along with other data. The important part is making sure all drives are back in the original physical location. If they are and you cannot rebuild the array, chances are real good there is a mismatch between the configuration on the controller and the one stored on the hard drive. If that is in fact the case, you may not be able to rebuild your array.
Thanks for the help. I am sure the disk order is right. I found a related topic as below. I followed the instructions, but it didn't work to me. I gave up, thanks everyone.