Windows Server 2008R2 Certificate Services will not start Error Code 0x80090011 (-2146893807)

For no apparent reason that I can find our server 2008 r2 server, which is our ca service has stopped. I have tried to restart it, but when I do, it says object not found. When I check the event viewer, this shows tha"Active Directory Certificate Services did not start: Could not load or verify the current CA Certificate. Object was not found, 0x80090011 (-2146893807)"

I believe that the root certificate's keys may have some how been corrupted or been removed.

What I asking is for some help and advice. I do not wish to uninstall the certificate services, as this would mean a lot of work else where, but to remove all the root ca certificates and keys, then to reinstall a copy of the ca certificate and keys into ca service.

I have tried restore from all tasks but I could not get it work. We have a copy of the root certificate with key where we had to export it to an application server. What I want to do is use this copy on the service.

Can someone please explain how to do this?