It's likely that your map (data) got corrupted. You can recover by restoring your back-up copy of the map (that you'd previously done via TomTom HOME on your computer).
If you don't have a back-up copy, try using your computer's disk check utility to fix the file system and recover data (from the storage media on your GPS device). Just connect the GPS to your computer, no need to use TomTom HOME, just use the Properties tab and use the Tools to run a disk check (assuming you're using Windows).
If that doesn't work, you may want to purchase & download and install the latest copy of the map from the TomTom website (via HOME).
295 questions posted
Usually answered in minutes!
Step 2: Please assign your manual to a product: