When you buy a map, you can reinstall for 1 year from date of purchase. First try using Update my Device option in Home and see if a map is offered for free. If so, dl and install it.
If not, log into tomtom.com with your account, then you'll see an icon at the top labelled My TomTom, click it. (You may have to click the Support menu first).
In the My TomTom screen, look on the right side under 'My Plus Services', under Maps, you should see your map listed. Click it to dl and install.
Once the installation is done, backup your entire unit using Explorer, not Home.
THEN............
Disconnect the unit properly!!!!!!!!!!!!!!!!!!!!!!!!!!!