Why do you get that Q and you wait for an answer/ Just use Unix 'find' command and pick the location thats relevant to vesion of the database to which you imported.

Its in ORACLE_HOME/rdbms/admin directory

And try compiling all the objects of SYS and SYSTEM.
And give a try. If you get 12154 try fixing tnsnames.ora.

Can I ask you a Q ? What made you to have this stuff as your responsibility. Its came on to you in no alternative situation or its your responsibility.

I mean, its hard to manage Just with forum. Especially Weekends. By any chance you have metalink access ? Iam advising you please request for metalink account and then only start working. Up to 70% of the Questions You will find an idea/solution with metalink, may not be direct, atleast indirect.
That helps you keep going with what has to be done, rather wait for some one's answer.

Don't take my Q otherway round. I could feel you having hard time on this. Thats why Iam suggesting...