This is a fairly easy quest. Talk to Gruthar and he is going to tell the Chosen One about the situation with the Vault 13 main computer, and how it does not respond to voice commands anymore. All the Chosen One need is a Vault-Tec voice recognition module. It can be found in two places; either bought from Eldridge for $3000 in New Reno by asking him for "something special", or found in storage in Vault 8, found in Vault City. Simply use the access terminal at the computer and install the module.