A silenced card loses its printed abilities and cannot cast spells. It retains its characteristics, its basic abilities, and any abilities it gains from other sources.
If a minion already has a Stealth or Ward mark and then is affected by Silence, it will retain the mark!
If is silenced, he will lose Immobile and be able to move, since Immobile is printed on the card. If a minion is in and is silenced, it will still be Immobile, since Immobile is being applied from another source and is not printed on the minion itself.
If is silenced, it will lose Flooded, since it’s printed on the card. If a site is Flooded via , , , etc. and then is silenced, it will still be Flooded, since Flooded is being applied from another source and not printed on the site itself.
If a minion gains Charge via or Airborne via and is silenced, it will retain those abilities since they aren’t printed on the card.