No signal No signal how do I fix it - GPS

You have not said what model garmin nuvi ?
The touchscreen on a Garmin nuvi GPS usually loses sensitivity or stops responding if it's lost calibration.
This usually happens after prolonged usage.
Touchscreen problems are also caused by dirt, smudges and improper care.
If your Garmin nuvi's screen isn't performing as expected, Garmin provides solutions and tips to not only improve the device's performance, but prevent premature wear and tear.
Calibrating the Screen

If the Garmin nuvi's touchscreen isn't working, you need to calibrate the screen.
Calibration resets and repositions the screen for optimal performance without deleting saved settings.
Before calibrating the screen, press and hold the "Power" button to turn off the device.
Pressing and holding the "Power" button again for about 30 seconds automatically displays the calibration screen.
Pressing the dot on the white screen calibrates the touchscreen automatically.

Updating Software.
If The Garmin nuvi's touchscreen is still unresponsive, updating the device's firmware to the latest version can solve operating system problems that lead to touchscreen problems.
Before updating the device's firmware, connect the GPS to the computer using the USB cable. When the computer detects the GPS, the "AutoPlay" menu appears on the screen.
Tapping the arrow on the menu automatically opens the "myGarmin Agent" download page.
From there, follow the prompts to update your Garmin nuvi's software quickly and safely.


Cleaning. In some cases, the Garmin nuvi's touchscreen won't respond to touch if the screen is dirty. Touchscreens are sensitive to dirt and smudges that decrease sensitivity.
If the screen is dirty, cleaning it with a soft, clean, lint-free cloth improves performance.
If the screen is severely dirty, using water, isopropyl alcohol or eyeglass cleaner removes tough stains.
To avoid damaging the screen, apply liquid to a cloth instead of directly to the touchscreen before cleaning it.

Tips.

Refer to your Garmin nuvi's maintenance and storage information found on the device's manual prevents premature wear and tear.
If the screen stopped working after prolonged exposure to extreme temperatures or water, the device's hardware is most likely damaged.
In such a case, you need to contact Garmin for additional troubleshooting and possible repairs.
Attempting to disassemble and repair the GPS yourself only increases the risk of damaging the unit even further.
also it could be a battery problem if the nuvi is not getting power ?