You can not. Simple like that. Go back and install a backup. When things like that happen and you are prepared, the results are not really that bad - as you can see on what happened to me recently - RAID 6 blowing in 5 minutes.
But your RAID has not failed.
It is degraded. Now, go and read the documentation for your RAID controller and learn how to deal with it. It will involve fixing the failed disc (replacing it most likely).
You should do so FAST - because the next disc failing blows the whole data. So make a backup. As you should anyway.
RAID 5 protects from 1 failing disc (BTW. you now have terrible performance due to that - technical limitation of RAID). Nothing is corrupt though and once you fix the discs (automatic or manual - depends on controller) things will turn back to green.