SUbscriber is stopped for 2 days due to SAN problem & restarted.Unable to catch up replication ,as undisributed commands are more than 20000000.

Getting error message(DIStributor to subscriber history)

Error messages:

The replication agent has not logged a progress message in 10 minutes. This might indicate an unresponsive agent or high system activity. Verify that records are being replicated to the destination and that connections to the Subscriber, Publisher, and Distributor are still active.

Any help is highly appreciated