Hi,
SO u want to get back the privileges granted to SYS.Login into Server Manager and then connect as internal (password:Oracle) and then grant all the necessary privileges to SYS user.

svrmgr>connect internal
svrmgr>grant dba to sys;

In case of any help please be free to ask me at [email protected]

Regards,
ROhit Nirkhe,Oracle DBA,OCP 8i
[email protected]