Can't install packages after a restore

[jai23155]

hi all, when i tried to uninstall squid and lightsquid packages, they neither uninstall properly nor working. so i have taken a full backup without packages information, then restored it from that backup. now i am trying ti install those packages without any luck. here is the error i am getting.
_Downloading package configuration file… done.
Saving updated package information... done.
Downloading squid and its dependencies... done.
Checking for successful package installation... failed!

Installation aborted._
please help.