Question!

My computer recently crashed from something i have no clue what. I had to restart it to factory settings and i was beyond angry. Now that I've calmed down, i noticed my Norton wasn't there (Obviously) and i wanted to know if i could simply pop the CD my norton came on and redownload it, or if i had to buy a new one... I really hope i don't have to buy a new one, as i can not afford it at this moment, and i just recently updated it. 

Can anyone help please?