Are you SURE you used the right key? Did you successfully test decrypt the partition boot sector (63) prior to starting the decrypt?
What sector range did you use when you ran the force decrypt?
What you should have done is decrypted sector 63 in the workspace to make sure the SDB you were using was the correct one.
Can you load up that sector in the workspace now and see it - does it look like a partition boot sector? Does it even look decrypted?
If there's no regognisable text at the bottom (it should say things like "missing operating system" then you either used the wrong SDB file, or you decrypted twice.
I think you'd be better off calling your McAfee support contact, confessing to what you have done, and hopefully they will be able to walk you through undoing the mistakes and recovering the machine.
you basically need to encrypt everything again with the SDB file you used to decrypt to put things back as they were, then start again with the right SDB file.
How you decrypt it and what do you mean "the process finished scornfully" ?
we need to understand what had happen to this disk to help you recover.
To avoid wrong key for decryption that need SDb file (exporting machine profile) normally i ask my user disk information
From disk information will tell us the Database ID and Machine ID
So search through Machine id from the manager and export it
and to double confirm can used workspace to verify again - by checking sector 63 as mentioned by simon.
It's should be fine if you used SBFS authentication.