When you purchased your license you were provided with the install file and your license information (name and ID) and told to keep these for future use. You will need both the install file and the license information to re-install. You also had the option to purchase a backup CD, which includes everything you need to re-install.
After your system is back in working order all you need to do is install the software using the install file you saved, then enter your license information into the software to re-register it.
Once the software is installed and your license information entered you will need to restore your data files from a backup or copy them to your new computer.