Changing subnet mask has killed network

Had a new router (juniper) placed in service today which required all subnets on my network to be changed from 255.255.0.0 to 255.255.255.192.

With this I am on the machines changed to the new subnet mask able to access internet, but no networkfiles. On the machines were the subnet mask has not been changed I can access the network files, but have no internet capability or email (webmail source).

The PDC and BDC’s (NT4) have both been changed to the new subnet and now cannot see each other.

Any advice?