Cannot Unlock Maps - Garmin Nuvi

If I look in the Garmin Foder on the device (where maps are usually found), I get Bing link to ust a Bing link : file:///C:/Users/wingreen/AppData/Local/Microsoft/Windows/INetCache/IE/L89CAHT4/GarminDevice[1].xml. - which doesnt exist.

I wasn't referring to looking at the device content using Windows, I was referring to seeing the list of installed maps.  Essentially using the procedure below.  

No idea how that link got there but delete it. 

There are lots of old .unl and .gma files. More recently another .unl file and another  .gma file plus an .img file which is 1,165,152kb. I can only assume that, for some reason, the "code" that comes with my Garmin has somewhow become corrupted?

What did you see under MapInfo as requested above?  Look at the dates of the .img, .unl and .gma files. Those with the same name and those file extensions should have the same date. Any older .unl and .gma files can be deleted.

If indeed either the .unl and .gma associated with the .img file have become corrupted you could try removing all 3 and see what then happens. Note remove, not delete, just in case you have to add them back.

Very strange. I removed all those files (but saved them). Connected Nuvi to PC and started Garmin Express. Strangely enough (although the Nuvi Map folder was empty when I connected to PC, Garmin Express said it N American maps on it!). Anyway, I used Garmin Express to "change" maps and chose the City Navigation UK & Ireland option. It went ahead and said it was putting those on my Nuvi. Took about 10 minutes. Express then said they had been loaded. But....when I looked on my Nuvi folders the Map folder was empty! (However the Garmin folder on my Nuvi, which had been empty before the update, now had a Bing link to file:///C:/Users/wingreen/AppData/Local/Microsoft/Windows/INetCache/IE/8RY1KWP9/GarminDevice[1].xml - which doesnt exist on my PC). The whole thing is very very bizarre.

Okay, I assume you are certain you're connected to the official Garmin website? If you are then I've never come across what you're reporting, I'd call Product Support tomorrow and seek their help.

Note the NA maps will be in the hidden .system folder, it's only secondary or additional maps that appear in the Map folder.

Since you’ve made some changes, again I’ll ask what choices do you have if you look at the nuvi menu, not exploring the folders using Windows.  

Product Support? Ha Ha. I phoned them end of last week. They eventually sent me an email which basically set out steps to try downloading again. That (unsurprisingly) didnt work so........they said I could have a replacement if I sent mine to them - at a (discounted?) cost of £129 (when I could buy one from a local shop for £99). I'm afraid thats it with Garmin for me - never buy a Garmin product. I'm assuming I must have been connected to the official website - it was via the Garmin Express app. 

I'm not sure which bits you mean. I've tried taking screen prints but I cant attach them here, it seems.  I do appreciate everyone's interest/help but it looks to me like its a lost cause. Thanks