Retrieving Serial Number/Key

Installed X5 on laptop but didn't register. Wife stepped on lap and  cracked LCD so I can't see screen. I have Westinghouse monitor but it won't work on this laptop.  I have new laptop but can't find the install disc. I have removed the hd from the old lap and can read it and access the setup file. It is asking for the serial number.  Is there a way to retrieve it?