If you have no pin in your unit, hold the power button down for 20-30 seconds. You'll know the tomtom has reset if you see the legal disclaimer screen with the "I agree" at the lower right.
You can see my long post in this link to understand how GPS works and what the GPS status screen is telling you. The detail screen has info that helps you understand/troubleshoot getting a signal at all.
https://www.tomtomforums.com/general-tomtom-discussion/16534-how-read-gps-status-page.html
In short:
Step 1: reset via pin or holding the power button
Step 2: Put the GPS in a location where you have at least 4 satellites on the detail GPS screen, and the height of at least 1 bar is 75% high, and wait until the GPS syncs (the bars change colors). This may be 5-10 minutes
Step 3: Go to the regular screen and keep waiting until the reception increase to 5 bars.
Step 4: Download quickgpsfix
After this everything should be back to normal.