After i log in a cant use the keyboard for typing or inputting text
1. Go to System Preferences (it's usually in your dock)
2. Click on Keyboard.
3. Make sure your key repeat rate and delay until repeat is set to fast and short, respectively.
4. Open TextEdit.
5. Try typing there. If this still does not work, I suggest you to bring it to your nearest apple store since there might be a defect on your laptop.
6. As an alternative, click SHOW KEYBOARD & CHARACTER VIEWER IN MENU BAR.
7. Beside your battery/energy saver preferences and date would be a small box, click on that and it will show you SHOW KEYBOARD VIEWER for you to use your mouse/trackpad on.