@shainyfonseka Hi, welcome to the forum!
Please read How to get the best out of this forum if you haven't done yet.
I makes answering questions easier if you provide clickable links to the devices you use.
Then it would be clear that you use a 3-color e-paper panel mounted on a display board from Waveshare.
Next step would be to take a look at diagnostic output in Serial Monitor, and eventually copy it to a code window in your post.
Most likely you need to use the init() method with the shortened reset pulse for this board.
Jean-Marc