Error :

RMAN-03002: failure of restore command at 05/10/2014 08:24:51
RMAN-06026: some targets not found - aborting restore
RMAN-06100: no channel to restore a backup or copy of datafile 17
RMAN-06100: no channel to restore a backup or copy of datafile 16
.....
.....

Solution :

rman target /

RMAN> list backupset
RMAN> crosscheck backup;

RMAN> delete expired backup;
It should Fix the above error .....

RMAN> crosscheck backup;

+++++++++++++++++++++++++++++++
Error :

SQL> alter database mount EXCLUSIVE;
alter database mount EXCLUSIVE
*
ERROR at line 1:
ORA-01102: cannot mount database in EXCLUSIVE mode

Solution :
Step 1:
ps -ef | grep ora_

Note: Please kill all ora processess if nay other db is running ... kill it .

step 2: start db using pfile
SQL> startup nomount pfile='$ORACLE_HOME/dbs/initPROD.init

SQL> alter database mount;