Acer aspire 5250 keyboard not working but mouse is

Hello,
I bought this laptop from friend which was locked with password. Another friend unlocked it by rebooting it I guess. It worked for 2 months then one day it said that I had to re install a driver with a long key code I guess which I have no idea what they were asking for. I tried to find this key code on the internet after asking another friend but found out that my mouse was working but keyboard is not. I have a USB keyboard hooked up now but very annoying and really want this laptop to work again. Some say I need to install a driver but I am very VERY VERY not computer smart at all and have no funds to take it into shop. If anyone could help by walking me through this process I will be so great full. Talk to me as if I am a 8 years old trying to set up an email account for the first time. Thank you to anyone that can help me please.......