First make sure that your Input is TV. Use the Input button on the remote (to the right of 0) or on the side of the TV (lowest button). To watch OTA channels, after connecting the appropriate antenna for your location with a coaxial cable to your Antenna In port, press Menu then use the arrows to select the Setup submenu. Press Enter to access the submenu and select Installation. Then select Terrestrial and then Input Configuration. Here select Antenna as your input. Press Enter to save. Then scan for channels by returning to the Terrestrial sub menu and select Channel Program to scan all available channels.
Since digital signals are either sufficient for your tuner to interpret or give No Signal, you need to select your antenna and point it with care. Go to anntennaweb.org
to get information on the stations that you should be able to get in your location. Antennaweb assumes an outdoor antenna but still gives a conservative list of available stations. TVfool gives stations depending on the color code of the antenna (indoor, outdoor, amplified) and their directions. If you are sharing the antenna signal with multiple TVs, you may need an amplified splitter. (If you do have an amplifier, you may want to test removing it from the line and directly connecting the 37HL17 to the antenna. When amplifiers get damaged they can turn into signal filters which block the signal completely.)
If you have the correct antenna, check if another TV receives the stations. If so, you may have a bad tuner on the TV. (Some TVs have better tuners than others and pick up the stations even with lower signal strength.)
I hope this helps.
(I use an outdoor antenna and antennaweb indicates that I should only get the stations from 10 miles away. I actually get those from 30 miles away as well. When I set up a neighbor's TVs with indoor antennas, one only gets the stations 10 miles away and the other gets the stations that are 30 miles away. The two antennas couldn't be rotated to the same direction.)