Hi,
I had already installed sql server 2017 in my machine and one of my application installed SQL server 2008R2 express edition on my machine to run itself. After installed application isn't worked properly as it couldn't connect the server because sql server instance is in stopped state. And I couldn't start the service.
Note: If I install that same application on the machine, where sql server 2016 was installed, it is working fine.
Thanks