Based on your comment that "the network team did some changes on server where we have deployer setup" the most likely issues will be:
Deployer not running (is it a service or an HTTP upload web application?
Firewall blocking the Deployer port from other servers (if the Deployer server is a Windows Server most likely it is the Windows Firewall blocking it)
Please check following:
restart transport service
connectivity between CM and broker DB
connectivity between CM and Deployer server [if CM and Deployer servers are different]
Check incoming folder in deployer server. is it receiving any package. in current situation it should not be. but it's worth to check.
revisit all ...