If the characters being typed do not correspond to the keys on the keyboard, it may indicate that the input language or keyboard settings have been changed. Here are the steps to restore the previous input configuration.
At login screen
1. At the bottom right hand corner of the screen where the date and time is displayed. Check to see if the letters next to the time says "US" or "CO" etc.

2. If the letters say something other that "US". Click on the time, a little pop up window will appear, then click on the option "Keyboard"
3. After clicking on the keyboard option, a pop up will appear displaying all language inputs available. Select the option "US"
4. After selecting the "US" option, try typing again to see if the changes reflect. If the change is correct, no futher action is required. If the change does not resolve the issue please let us know and we will investigate further.