How can attach 3 router with one switch

Hello,
I have three different network with different static IP's and I want to connect those routers with one switch. If any case any network gos down then another taking care automatically.
Is it possible? If Yes, please give me the name of switch.

If you are running static IP addresses on your network and not dhcp then you should just be able to plug them into any switch, this would be a manual approach to fail over. This would require the IP address to be switched on local machines, unless all the routers have the same IP address and etc... You can always run a VLAN and just switch the cables in that case. I would recommend a Cisco managed switch. You can find them online for pretty cheep and that would do the trick.

If I may ask have you looked into dual/multiple wan port routers that would do load balancing and automatic fail over? That might be the way to go unless the routers were a new buy.