How did it happen that you got into the "No map found" ditch? What was done just prior to this? Is there any reason that the map files should have been deleted? If you look inside your device in the folder called "USA_Canada" or something with the words "North_America" in it, do you see largish files called cline.dat, poi.dat, cnode.dat and cname.dat? If those files are present, we might be able to resurrect things.
Did you ever download a new map for your device? Perhaps it was on another old PC that you might still own? When was the last time you can recall updating your XK350 map? If you check in the file ttgo.bif in the root of your device with any text editor, there will be a line in it some 30+ lines down that says "CurrentMapVersion=". The age of the map set we see there may tell us the last time the map was updated.
You've done right to look for a full map download. Did you check Home to be sure that the path you are searching is correct?
With HOME running, selecting Tools / HOME Preferences / Folders will show the exact path that it is using.
While you are checking that, also have a look at the "Backups" folder path. The other option for finding a full map for your device would be if you had ever backed up your TomTom. Anything there?
There was a time when you could sometimes beg a map from TomTom under such circumstances. The GOOD news is that they are still likely still producing maps for the XL350TM. They have been honoring the "M" part of the bargain even though these devices are quite old. The bad news is that the XL350TM didn't have an SD or uSD card slot, and the current Nav2 US/Canada map (2.4GB) hasn't fit into the internal memory of an XL350 (2GB) for quite some time. But they may still be offering map segments -- e.g., just Canada -- for a reasonable price, if it comes to that and you're willing to go that route.