If you don’t know then you’re not. It’s not easy at all to create as service!!!
Okay, a simple uninstall/reinstall should not cause you network issues unless a firewall is blocking.
I would first like to say you don’t need to uninstall pms from c: because the space is running low. All you need to do is tell plex to use a different metadata path(D: i guess in this case)
Oddly enough, I would uninstall then reinstall back to c:\program file…etc.
I say this cause the original setup you had worked. No need to over complicate the situation.
When you have completed this and plex is online. make sure all looks good.
Now follow these instructions.
Follow them one-by-one and you will have no problems.
Let us know if you run into issues.