raid 0 - its not getting fixed, you will need to restore data from your backups once you figure out how you will proceed (replace the drive & create another raid or run with only 1 drive).
raid 1 - All your data is on the good drive. Replacing the failed drive should kick off a rebuild sequence which probably will take a day to complete. If not force the rebuild manually. See your raid documentation for how to do that.
JBoD - all the data on the failed disk is gone, you will need to restore from backups once you determine how you want to proceed. You will also need to reinstall any software that was on that drive, OS included.