What should I do regarding people whom I lent money to and they did not pay me back, and now they are asking me for another loan? And do I lose the reward if I speak about their failure to repay my debt?

A good loan (Qard Hasan (definition)) is Islamically recommended because it relieves a Muslim's distress. The Lawgiver (Allah) has encouraged it and promised great reward for it. The reward is not invalidated by demanding that a wealthy procrastinator pay his debt, or by speaking about his procrastination, because a procrastinator is an oppressor. As for the one in hardship, he must be granted respite until a time of ease.