If you are having problems reconnecting NFS datastores, run the following on the ESX server after connecting with SSH.

As ever, take care when running commands on your ESX servers.

Code:

1. List NFS datastores with esxcfg-nas -l
2. Remove inaccessible datastore, esxcfg-nas -d datastorename
3. Readd the datastore,  esxcfg-nas -a -o hostname -s sharename datastorename 

Virtual centre should then show that the NFS share is accessible.