Hi,
Due to the fall you may either have a loose video cable connection or a faulty connection inside the display panel itself
Just to eliminate a further possibility of a motherboard problem, If possible try connecting an external monitor to the laptop and check it the display on it is OK or not. A TV can be used as an external monitor as long as it has a HDMI input and you have a HDMI cable with the appropriate connectors to connect the two together.
Here’s a link to the [http://h10032.www1.hp.com/ctg/Manual/c04493435|service manual] for your laptop, taken from this [https://support.hp.com/us-en/product/hp-chromebook-14-x000/7277301/model/7547744/manuals|webpage].
Scroll to p.38 to view the necessary pre-requisite steps and then the procedure to remove the display panel. Doing this will allow inspection of the video cable connection on the motherboard to make sure that it is seated correctly. After that the LCD panel will need to be removed to check the cable connection at the other end and also possibly if the connection appears to be OK, the replacement of the LCD panel.
The manual has the part numbers for the panels, (see p.46, usually it is stamped somewhere on the back of the panel itself if you wish to verify which is your panel part number)
If you search online using the ''part number only'' in the search term of your browser you’ll get results for suppliers of the part.