Could Not Connect To Com3

Hi,
I have a usb cable from pc to 3D printer.
At first when i hit connect on the pc it just said connecting but nothing happened.
I tried again & this time it worked fine.

Some time later i went to use the same software but when i now click on the same port then click on connect i see the following message.

[ERROR] Could not connect to COM3 at baudrate 115200:
Serial error: could not open port COM3: [Error 2] The system cannot find the file specified.

Looking in device manager i see COM3
If i unplug / plug in again you here the ding dong tone.