Perhaps something is interfering with the signal. Or, the antenna in the power cord is bad. You didn't swap out the power cord, did you?
A test of interference would be by taking the Roku Stick and connecting it to a TV that's much closer to your router. If that work, then it's highly likely it's something interfering with the wireless signal.
I tried a TV a lot closer to my router and the same thing happened. I still get a blinking white light and the Not Connected screen.
That does not bode well.
You said you did a "reset." Ensure you do a Factory Reset this way: while plugged in, hold down the Reset button on the device for at least 30 seconds. Not 29, or any length less than 30, but for a full 30 of continuously holding the reset button. If it slips off the button, start the count over. A full 30 seconds.
If that doesn't do it, and you are in range of a good network signal, there may be an issue with the Roku or the antenna.
I tried what you said and it didn’t work out. Should I try and purchase a new cord? Is the antenna in the cord? I have the Roku Streaming Stick-3600.
Honestly, I'd suggest just getting a new device. While the 3600 was a very good device, the current Stick+ is head and shoulders above it. I wouldn't suggest putting any more money into a device that dates from 2016. There would be a noticeable improvement in responsiveness from using the Stick+
I hate to have to suggest replacing a device, but it may be time.
Before scrapping your device, this might be worth a try:
If that doesn't fix it, try disconnecting the power to your Roku for a few seconds. When it comes back up, see if you then can set up the network connection.