How to add LAN driver?

I used sudo dkms remove r8168/8.046.00 -k 4.18.0-17-generic In order to fix unstable LAN connection. Since then my laptop is not detecting LAN. In the meanwhile, I have upgraded to 19.04 and hope that the issue is resolved. How do I get back LAN. I tried sudo dkms add r8168/8.046.00 -k 4.18.0-17-generic , but it did not work.
For sudo dkms add r8168/8.046.00 -k 5.0.0-13-generic I get Error! DKMS tree already contains: r8168-8.046.00.
When I try sudo dkms remove r8168/8.046.00 -k 5.0.0-13-generic I get Error! There is no instance of r8168 8.046.00.