DB startup error

Hi. Experts.

I am getting the error below while starting the oracle 11g database.

ORA-01261: Parameter db_recovery_file_dest destination string cannot be translated
ORA-01263: Name given for file destination directory is invalid
OSD-04018: Unable to access the specified directory or device.
O/S-Error: (OS 2) The system cannot find the file specified.

Experts Please Help.

Thanks

Mohd Basis