sometimes the oracle profile is not prepared correctly and this give so many errors and you should go direct to directory of SqlPlus to start DB
./sqlplus sys/password as sysdba;
the following error will arises
ORA-12162 TNS:net service name is incorrectly specified
This arises if you have not set ORACLE_HOME and ORACLE_SID.
you can fix it by setting the ORACLE_HOME and ORACLE_SID as following
> export ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1 > export ORACLE_SID=ECMTEST and try to start the DB ./sqlplus sys/password as sysdba; sql> startup force;