Depending on the way you deleted it (you don't tell) it might still be in the Recycle Bin. That's the easy part.
You can try system restore, but you only know if it works if you've done it.

Luckily, MS Works is not MS Office, but a cheaper product. So it will cost you less money to buy it, even packaged with MS Word.
But why don't you switch to free Open Office ( It's more powerful than Works.