Ora-01033: Oracle initializationg or shutdown in progress error prompt

This problem is generally caused by data file loss or damage. You can perform the following steps:

1. Go to CMD and run set oracle_sid = fbms to ensure the correct Sid is connected;

2. Run sqlplus "/As sysdba"
SQL> shutdown immediate
SQL> startup start the service, observe that no data file loading error occurs at startup, and remember the error data file number.
SQL> shutdown immediate stop the service again
SQL> startup Mount
SQL> recover datafile 2 restore the wrong data file
SQL> shutdown immediate stop the service again
SQL> startup starts the service. This time it is normal.
3. Go to PL/SQL developer for check. No error is displayed.