Problem connecting to Oracle database

I have an oracle database instance on my local machine that I am trying to connect to.

Using SQL Developer, I can connect to it. But when I use sqlplus, I can not connect to the instance.

The error message I get is

ORA-28547:connection to server failed,probable oracle net admin error.

I tried to restart the TNS service, but the problem still persists.

And I need to connect to sqlplus because I need to import dumps using

impdp system/***** schemas=abcd dumpfile=DUMP_500.dmp 

Please let me know what other information is needed so that I can post

thank