Instructions
Find the Fallout.ini file in the game's directory, located by default in the FalloutNV folder.
Right-click the file and select "Copy." Back up the file by copying it to a different folder or your desktop.
Right-click the original Fallout.ini file and select "Properties." Click the box to remove the "Read-only" permissions.
Launch the game and load one of your saved games. Press the ` key to launch the Gamebryo console. Now you can edit the game's INI file with command line entries.
Enter "resurrect." without the quotes. After the period, enter the NPC's reference ID. A list of reference IDs is available if you download and browse the New Vegas Garden of Eden Creation Kit (G.E.C.K.). Enter the corresponding command line and then exit the console.
Visit the NPC's normal residence or location. If the NPC was deceased, unconscious or missing due to a glitch, the NPC's location will be reset to a default location.