you will need to provide a lot more information than that;
make & model, time in use, connection, etc.
plus images of the screen showing the issue.
also include all of your system specs.
usually artifacts on screen are due to graphics card failure.
try your display with another device and see if the problem remains.
just "pressing" any display wouldn't damage it unless you very roughly hit the screen.
even in those instances that i've seen there was usually just an off-color or cloudy section where the impact occurred.
though it's possible that you have loosened the connection to the screen.
it's also possible that you have just damaged or loosened the connected display cable if the monitor slid across the desktop or "jumped" in...