My hard drive crashed and I had to replace it but now my subscription key doesn't work. What do I need to do to start my F-secure again
Since this is the beta forum I assume you're using beta version.
Just login to beta.f-secure.com, get the installer from there and install. The installer contains the subscription key and automatically uses it.
F-Secure R&D, Desktop products
There is no need to ask support to reset the key any more. If all subscriptions are used the client offers an option to move a license from another computer.
That's excellent news!