if you're 64 never have been sick never taken full holidays have always put in a great performance and all of sudden you're let go when they keep the younger employees can you sue?

It is a matter of severance. They are allowed to let you go, so long as they pay you all the severance that you are owed. Most employers don't do this. To see how much you are owed, check out the calculator and then give me a call: www.severancepaycalculator.com