Firstly have you checked to make sure that your personal Names.nsf is on the right place.
location will either be
c:\program files\ibm\lotus\Notes\data (single user install)
\local settings\application data\lotus\Notes\data (multi User install)
There are different ways to confirm what install you are running but search for Notes.ini will no doubt show you the correct location faster than searching the registry.
Then if the Names.nsf is not there then simple restore or recreate the DB.
Simple way to recreate the Names.nsf is to reconfigure the Notes client…. to force this open the Notes.ini and delete all rows below the DST line. Then start Notes….. this will then prompt you to reconfigure notes.