But let's start with common ones that are easier to handle.
1. Power off then unplug ALL USB connections. Try again.
2. Try SAFE MODE.
After this it gets harder as we boot up our W8 or W10 rescue DVD or USB stick to look around.
Since SAFE MODE is documented on the web I pause here.
After I enter password, the egg timer icon just keeps spinning & nothing else. I cannot access anything? Lenovo laptop. Any help appreciated. Thanks