A table can not be access

Hi  

I have a rac oracle 9204 ,IBM p570 aix5304

And I tried to delete a foreign key by

ALTER TABLE BN_MAINS DROP CONSTRAINT BN_MAINS_FOR I don¡¯t know what was happened

It¡¯s possible the delete operation have not completed

The table bn_mains cannot be access

For example , when I run

Desc bn_mains

In sqlplus, then sqlplus hang  

How can I return it?

Thanks  

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