If you install software with windows, you may see the error message:

The drive or UNC share you selected does not exist or is not accessible. Please select another.

To resolve this problem, you need download CCleaner portable, which help you out.

https://www.ccleaner.com/ccleaner/builds

After download it, you open ccleaner, find the section: Tools => Uninstall

Check the list, find out you want to install? for example, i install git and face the error: The drive or UNC share you selected does not exist or is not accessible. Please select another.

So i choose Git from the list, and choose delete

After you confirm delete git , try install git again, the problem is gone.