ORA-19625: error identifying file

Firstly, check if you have gaps in standby, see following link for resolving gaps

Gaps Resolution
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/scenarios.htm#SBYDB01515

Managing physical standby
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/manage_ps.htm#SBYDB00700

If problem is not solved, you may have deleted archived logs using operating system commands. Then try these:

     RMAN> crosscheck archivelog all; // validate all archvelogs in your disk. If some are missing, it will treat it  as expired.
    RMAN> delete expired archivelog all; // it ill delete expired archivelog and updates your controlfile.