what shall i do? i have forgotten my old listening port
Select a new port, something between 49000 and 65535. I recommend using a Ouija board to choose.
Write it down. Use a sharpie. On your hand. Or forget all that and just choose a port you can remember. How about “65432”?
Set that as your listen port. If your hand tries to click “Choose random port”, cut it off at the wrist.
Now set that as your new bitcomet port in your firewall. If there’s grief about changing it, delete the old rule and add a new one. Make sure you’ve closed the old port. If you’re using a router, change your port-forwarding rule to reflect the new port.
Make sure the port is open for both TCP and UDP. Test it to make sure it’s really open.
And, oh, just ask a question once, there’s no need for multiple topics on the same q.