The middle button was helpful addition to mice and has been there for quite a while. The middle button in the mouse is used to scroll the mouse pointer and a single click on the same could be customised for functions like opening new tabs, etc.
However, many users have reported that the middle button in the mouse stops working suddenly. The issue is usually with the system more than the mouse itself.
Isolating whether the issue is with the mouse hardware or system
Try plugging the mouse to a different system and check if it works with the other system or not. It it does, we know that the problem is with our own system.
Try the following preliminary steps one by one to resolve the issue:
1] Use the Hardware and Devices troubleshooter. (Go to settings -> Update & Security -> Troubleshoot)
2] Update/reinstall the mouse drivers. Here’s the procedure to update drivers.
3] Run a full virus and malware scan of your system.
4] Uninstall Recently installed suspicious programs.
We could proceed to the following solutions thereafter:
Solution 1] Set mouse settings to default
The issue could have been caused if you fumbled up with the settings of the mouse. You could set the settings back to default to isolate this possibility. The procedure to do so is as follows:
1] Click on the Start button and then the gear-like symbol to open the Settings page.
2] Go to Devices and then the Mouse tab.
3] Click on Additional mouse settings.
4] In the Device settings tab, click on Settings.
5] Select Defaults to set all the mouse settings to Default and then click on Apply and the OK to save the settings.
Solution 2] Registry level fix
1] Press Win + R to open the Run window and type the command regedit. Press Enter to open the Registry Editor.
2] Navigate to the key HKEY_CURRENT_USER\Control Panel\Desktop.
3] On the right-pane, double-click on the entry WheelScrollLines to open its properties.
4] Modify the value of Value Data to 3 and click on OK to save the settings.
5] Exit the Registry Editor and reboot the system.
Hope it helps!