RAID 5 lost ! Will beg to help me.

Hello everyone,
will "beg" to help me!

I do not speak English well and then I rely on google translator. Forgive me for any mistakes !!!

Yesterday I found the sharing of nos. I checked the system, and I saw that the raid was not on! I checked with the gui, and I saw a failed disk. The disk sdc.

I turned off the system, I replaced the disc, I rebooted
I replaced the hard drive but the raid does not start! I do not know what to do.

The version is 0.5.24 Openmediavault

Type RAID: RAID5

Disk:

Disk 1 /dev/sda - System Disk
Disk 2 /dev/sdb - Raid
Disk 3 /dev/sdc - Raid
Disk 4 /dev/sdd - Raid

These answers to some commands:

mdadm -E /dev/sd* | grep event

root@aq:~# mdadm -E /dev/sd* | grep event


mdadm: No md superblock detected on /dev/sda.


mdadm: No md superblock detected on /dev/sda1.


mdadm: No md superblock detected on /dev/sda2.


mdadm: No md superblock detected on /dev/sda5.


mdadm: No md superblock detected on /dev/sdc.

cat /proc/mdstat

root@ag:~# cat /proc/mdstat


Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 


md127 : inactive sdb[0](S) sdd[2](S)


      1953523120 blocks super 1.2

mdadm -E --scan

[/b]root@ag:~# mdadm -E --scanARRAY /dev/md/raidnas metadata=1.2 UUID=034dc6dc:4da0603b:76e70c58:1fb4cc0a name=ag:raidnas[b]

[/b]What can I do?

Thank you

I also tried it with this command:

root@ag:~# mdadm --assemble --run /dev/md127 /dev/sdb /dev/sdc /dev/sdd


mdadm: cannot open device /dev/sdb: Device or resource busy


mdadm: /dev/sdb has no superblock - assembly aborted