To reset the sys password of a database, do the following:
1) rename/delete ${ORACLE_HOME}/database/PWD{ORACLE_SID}.ora
2) enter the command: orapwd file=${ORACLE_HOME}/database/PWD{ORACLE_SID}.ora password=newpassword
3) start “sqlplus /nolog”
4) login with sys and the newpassword (SQL> connect sys/newpassword as sysdba)
5) now reset other passwords or just be done