When you went to TOOLS did you press SETTINGS and then MAPS and at the bottom of the screen MAP INFO.
When you press map info if the maps are still installed they should appear there. If there's not a tick beside the map name then it's unselected. Pressing the map name gets it selected again and could solve the problelm.
If you do need to download the maps again it may be possible, depending on how long it's been since they were downloaded or updated. (Usually it's possible for around 6 months after they were originally downloaded.)
- Go to www.garmin.com and click the myGarmin tab at the top of the page. Log in using your username and password.
- Click on the myMaps tab at the top of the screen and you should see your maps displayed.
- Under your latest update you should see in blue writing a link called DETAILS
- Click on the link and then at the next screen click on DOWNLOAD AGAIN
When you're following the prompts you'll come to one which gives you the option to download to the Satnav, Satnav and computer or Computer. Select Computer or satnav and computer. Then if you have a problem again with the map it will be easier to install it from your computer. You can find more details on installing from your computer and indeed all about updating your map at http://www.fixya.com/support/r5628920-update_garmin_satnav_maps
If you find that your map cannot be downloaded again buying a new update, if there's one available should solve the problem.
If you find that your map is locked you can get information on unlocking it at http://www.fixya.com/support/r6197735-no_detailed_maps_found_support_routing
If you have favourites saved to your satnav it's a good idea to back them up to your computer just in case you lose them. Details of how to do this are at http://www.fixya.com/support/r8422587-backup_restore_favourites_garmin_nuvi