I installed raspbian stretch on my Rpi 3 and it works perfectly using HDMI display. But when I run it using ssh on my laptop. I cannot connect it using the ethernet. My laptop sends the packets but it does not receive them. when I ping it says "Request timed out". Please help I'm trying to connect via ethernet
Sometimes your hostname and IP are not in up-to-date. try connecting via the RPi IP address instead of its hostname. If that works, then you know the problem (or better, you know the Pi is not the problem). If it does not work, you'll have to dig deeper. Is ssh enabled? By default, a fresh install has ssh disabled and you have to enable yourself.
To enable it you can either run
sudo raspi-config, or, if you still have the sd mounter on your OS (the one you used to copy the image to the sd), you can create an empty file in the boot partition of the sd, named 'ssh', and that's it.