the worth of this program, Cubase, is applied to the license, you got on your USB-eLicenser. if your computer is crashed, usually it should nothing matters to, because you bought the programm as a license to work with for unlimited time, which you got on your USB-eLicenser. Did you registered your License on the Steinberg-website? when you´ve done this go to your mySteinberg-account on the Steinberg-website and look for that number. if you´ve not registered the license, it mabye is a little bit more difficoult. go to the eLCC (eLicenser control center) and look on your license you got on the eLicenser.
if you aint got the eLCC, you can download it from the Steinberg-website, here: http://www.steinberg.net/en/company/technologies/elicenser.html
where did you bought Cubase, when you´re not sure, if you ever got an activation code?
PS: which version you got of Cubase?