As long as you still have your TFT CD key and ROC CD key, you can reinstall via downloading the data off the internet and using your CD keys to install (should not be ilegal as you payed for the game already). Thanks to the no CD patch, you can also play without the orignal discs as well. However do not bother asking where you can download it here as we will not support you doing so and will not give links to any site or place where it can be downloaded no matter how much you ask or beg us. Discussing downloading of games here we will not tolerated and I only mentioned it as in this case as you owned a legitimate copy of TFT and it broke you can legally aquire it as you already payed blizzard for the game.
If you really threw away everything (CD key included), then you have no choice but to buy it again.