If your controller will not connect to the sim or if you are only getting the No Hardware message at the bottom of the screen, please double check that the Steam Input Per-Game Setting is set to Forced Off/ Disable Steam Input in in the dropdown menu in Properties.
The Properties menu can be accessed by right-clicking on DRL Simulator in your Steam Library and selecting Properties. Then click on Controller. 
The next thing we want to do, is adjust the General Controller Settings in Steam.
To do this, click on the word Steam in the top corner of the Steam window.
Then click on Settings (or Preferences on Mac) and the Settings box will appear.
Please click on Controller, and then General Controller Settings. 
This will open a NEW window, please uncheck all boxes, except the top one. See image below. 
Once done with this, please close all the extra windows, and launch the DRL sim.
Please attempt to go through the Quick Calibration process in the Controller Setup section from the in game Settings. 
If you are still having trouble, please send us a Help Ticket so we can assist you one on one!
Thanks!
If the Above does NOT fix your issue and you are using an "OPENTX" radio (FrSky/Jumper), please refer to the following link.
https://drlracingsimulator.zendesk.com/hc/en-us/articles/360033368392-Taranis-Jumper-Controller-Stopped-working-out-of-nowhere-OpenTX-Windows-issue