Hi Ron,
I've just returned from licensed premises (hic!), so I don't guarantee that this answer will be as precise as it might otherwise be ;-)
It seems that, for some obscure reason, your 'file associations' have gone wrong. You can circumvent these 'associations' by opening VLC, going to File > Quick Open File, navigating to the location of your video files and double-clicking on the relevant file.
To correct the 'file association' (so that you can simply double-click the relevant file and open it in VLC), right-click on any FLV file. Choose Open With > Select Program. Ensure that there's a tick in the box labelled 'Always use this program to open these files'. Select VLC from the menu and click 'OK'.
( If VLC doesn't appear in the menu, you'll need to select 'Other', navigate to the location of the VLC program (which is probably in a folder called Videolan, in another folder called Program Files, on Drive C), and double-click on the VLC program file ).
Chris