DISKGROUP DISMOUNTED

Hello,

I have a problem mounting one of my asm diskgoups containing very important datafiles.

I had the following error when i tried to mount the diskgroup.

Is there a way I can mount the diskgroup again or reasign the disks in the diskgroup to a new diskgroup without losing the data on the disk?

SQL>
SQL> alter diskgroup ORADATA mount;
alter diskgroup ORADATA mount
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15066: offlining disk "ORADATA_0001" may result in a data loss
ORA-15131: block 9 of file 1 in diskgroup 2 could not be read
ORA-15196: invalid ASM block header [kfc.c:6886] [endian_kfbh] [2147483649] [9]