my mist is not syncing in private network and it did not show the ethers. so I need to uninstall Mist permanently and again I want to install .But when I install the mist it shows the older mist .
It is most likely your blockchain not syncing, try
delete $home/Libary/Ethereum/chaindata this should wipe out the blockchain itself and let you sync from scratch.
delete the entire $home/Libary/Ethereum folder (backup your keystore folder, which is your wallets before deleting, very important!!)
geth removedb to remove the blockchain and state databases.