A very helpful command to reset the current ospf process is:
clear ip ospf process
This restarts the process and let OSPF re-establish adjacencies.
What i found out, ist that the router-id does not change, when you have set up another ip address for a loopback.
But then resetting the OSPF process with the „router-id“ command is successful.
So for example the current router-id is 1.1.1.1 because of loopback0 with ip add 1.1.1.1 and you change the ip address of loopback0, the OSPF process does not update the router-id, even with „clear ip ospf proc“ not.
„router-id“ does reset the OSPF process too. So setting it and then removing with „no router-id“ would do the trick. Anyway, you can of course set the right id before. Just to mention that. Hope i made that clear. 🙂