are you winning games or not? I have never had more than 1 player unhappy ever.. nor more than one poor morale, its always very good to superb...
you need to MANAGE your squad better! keep all the players happy so they do not disrupt the rest of the team, they will immediately be unhappy with you if you try and terminate their contracts... that was a schoolboy error and a complete waste of money.. (which even your board wont allow)
start playing some of these players in a few games, even sub them in for a few minutes or so, just give them 1st team football and play them in the smalller Cup games...
once they are happy again their values will go up and it will be a bit easier to sell them, try and loan them out, ask for 50% of their wages to be paid for (at least its something) and let their contracts run out if you want to do it like that..
there are many options bud, choose the correct one!