You can't use a database when it's being restored.

That said, if it's been restoring for a while - it's possible the restore was done incorrectly.

You didn't give enough information to really figure out what's wrong, so I'm going to make some guesses here...

Look at the database in Enterprise Manager, does it show LOADING?

If you are not actively restoring the database, but it's still in a restoring state (LOADING) that means that the option WITH NORECOVERY was probably used and the database is awaiting another file to be restored.

Try running this command:

RESTORE dbname

WITH RECOVERY

Change the dbname part to the real name of your database.

-SQLBill