It can be frustrating, especially if you are trying to do it all in one step.
Break it down into smaller steps.
First, try out the servo sweep tutorial.
Confirm that you have the servo wired properly and that you can get it to move where you want from code.
Second, unplug the servo and work on the keypad. Can you get the serial monitor to display 1234 when you type 1234?
Third, unplug the keyboard and try the display. Can you get it to display text from your sketch?
Finally, start working on combining these steps into a single sketch.
Try it out. Let us know how it goes. If you get stuck, we will be glad to help. Post your code using code tags, explain what you expected. Then explain what actually happened that is different that what you expected.