When I start the Windows, it say the C:\WINDOWS\system32 missing nvktkf73.dll?

Answer 1

The file that you mention does not appear to be a windows system file, It might be an dll used by an uninstalled program. Run the following two menus of ccleaner that will remove the entry from registry and you will not see that warning again.

-cleaner > Analyze > Run Cleaner
-Issues > Scan For Issues > Fix Selected Issues

Answer 2

your going to need to use your windows cd and see if u can repair it or ucan find some dll sites that give you free downloades and see if ucan fix it like that