Yes, if you delete the partition, you'll make it much harder to recover the data. Try to use a disk recovery utility to get your data back, like testdisk.
The first thing is to back the drive up to another HD. This is because you do not know what caused your problem in the first place. After backing up, you can test the drive for reliability. Do not trust any software with your data in mission critical situation. As long as your data is safe you can do to the drive to fix it. Remember even software designed to recover partitions may cause further damage. BACK UP FIRST!.
Steve