Rollback command not working - Oracle

Question

I dropped a table and tried to rollback, but to no use. Will it ever work like this or am I playing wrong here?

As from most of the comments I am clear that DDL statements cannot be undone by rollback but only by FLASHBACK.

I tried undoing DELETE FROM STUDENT;

It still it can't be undone:

My order of execution was

• INSERT,

• DELETE FROM ,

• ROLLBACK.