If a repair did not work, you may be able to rebuild your database like
this:
1. Make a copy of the file while it is not in use.
2. Open the relationship window (Tools | Relationships), and delete any
relationships that the problem table is involved in.
3. Open the table in design view. Open the Indexes box (View menu), and
delete everything in this box. This includes deleting the primary key index
(though you do not delete the actual field itself). Save. Close the table.
4. Compact the database: Tools | Database Utilities | Compact. Close the
database.
5. Create a new (blank) database: File | New.
6. If this is Access 2000 or later, uncheck the Name AutoCorrect boxes under
Tools | Options | General.
7. Import everything into this new database: File | Get External | Import.
8. Test that your table is working okay in the new database.
9. Open the table in design view, and create the indexes that you deleted in
step 3. Save. Close the table.
10. Open the Relationships window, and create the relationships this table
was involved in.
The whole process should take less than half an hour, and get you back on
the road again.