i have messed up my tomtom xl one and i never backed it up...l know l'm stupid and should have but now what can i do ?? does anyone have any ideas on what i can do to get it back up and running.....please help i keep getting a screen that says.."can not use this maps on this device
Try the following:
1) Plug your TomTom to your PC
2) Make sure TomTom HOME is not running by right clicking on the HOME icon in the lower right application tray of Windows and clicking "Exit"
3) Using Windows Explorer, find your TomTom
4) Make a backup of your TomTom by copying EVERYTHING from your TomTom into a folder on your PC using Windows Explorer
5) Once you are
sure you have a backup of your data, delete everything from your TomTom.
6) Once you have deleted all files, run the TomTom Clear Flash Tool:
>>> Clear Flash <<<
7) Once the Clear Flash tool completes, open up TomTom HOME...
8) HOME should recognize that you have a TomTom plugged in but that there is no TomTom Operating System (called TomTom Application).
9) If home gives you the choice to install the TomTom Application, go ahead and do that.
10) Once you've installed the operating system, go to the TOOLS menu in TomTom HOME
11) Click on "Use Latest Map Guarantee"
12) HOME should see that you are permitted to use the Guam and USA_and_Canada maps and allow you to down load and install them.
13) When HOME shows the maps to download, go ahead and download and install.
or more here 
