If your laptop isn't starting properly you can follow these steps. 

This will not delete any data or settings. It will only reset the laptop.

Option A: 

Step 1. Make sure the laptop is turned on (the light of the power button needs to be turned on).

Step 2. Hold the power button for 35 seconds and release the power button again (this will force the laptop to completely turn off).

Step 3. Wait 5 seconds and turn the laptop on again with the power button.

Step 4. Wait until Windows has completely started.

If this doesn’t work you can follow option B.

Option B:

Step 1. Close the lid (screen) of the laptop and place the laptop upside down on the table (you will now see the bottom of the laptop)

Step 2. Get a stapler and take one staple. Bend it open. This staple has the size of the little hole on the bottom of the laptop. This is a reset button. (it will only reset the laptop, it will not delete any files) Place the staple in the little hole, you will feel that a button is pressed. If you don’t feel the button try again. Make sure that you keep the button pressed for 30 seconds.

Step 3. Flip the laptop back on its proper side and try to startup the laptop.

*Note: this is a Lenovo Yoga L13. As you can see the button is located in the middle of the laptop.
The location varies with other models of Lenovo laptops.