My Arduino UNO turns LED ON forever when I connect it to my Laptop
When you connect the device, if you hear the Windows "found device" sound, then you need to check your COM port driver, as it's very likely that the COM port number may have changed. On your Desktop or in File Manager, right click "This PC" or "My Computer", and select "Manage" from the submenu.  That will bring up the Computer Management console. On the left, select "Device Manager".  That will bring up your list of devices. In the list look for "Ports (COM &amp; LPT)".



If you don't see, "Ports", then click "View" and check "Show hidden devices".  If this is the only Arduino that you've ever used, you should only see one listing. Make note of the COM Port Number the driver is using. It's possible that the port number may have changed since you first used the device. Plug-n-play will do this if you plug the cable into a different USB port that may be using a different USB controller, etc.

Then in your Arduino IDE, click "Tools", then expand "Boards" and select "Arduino/Genuino UNO" board, then re-click "Tools", and hover over "Port", and select the port number that is assigned to the Port that you found in Device Manager.

If that doesn't work, then you may have a problem with your driver.  Some of the "cheap chinese board" use a different FTDI chipset, so the plug-n-play windows driver may not work. In that case, the manufacturer should point you to the correct driver. Download their provided driver, then you can update the driver in Device Manager.