In the first case, generally, a Buddhist should not sue other people, but it depends on the circumstances. Suing has to be of benefit to others.
In this case, it comes out better to sue. If you have to do this, do it with compassion. Avoid unpleasantness to others. By having compassion, you protect yourself from the negative karma of causing unpleasantness to others.
Continue trying for another seven months with this motivation: “I will use the money that I get from this for the benefit of sentient beings.” In that way, it becomes positive, virtuous, and a cause of enlightenment. Think: “I will not act out of hatred toward others.”
Recite the Amogapasha mantra every day, as often you can. Make tea offerings and incense offerings every day.
In the second case, according to my observations, it seems difficult to get the money back from them. It seems impossible. You can use this in your Dharma practice. By doing so, when others can’t pay, what you receive from them through your Dharma practice is much more than if you got your money back.
First, to have the right motivation, think: “I am going to offer charity to all sentient beings, offering them all the money that I have loaned to this company.” Even though this money didn’t actually go to sentient beings, if you dedicate it from your heart in that way, you collect the merit of offering it to them.
Remember that the Buddha sacrificed his life to sentient beings many hundreds of times over, for three countless eons. The reason for doing this was because other sentient beings need happiness, and do not want suffering. To accomplish these aims, you need the two collections of merit: the merit of wisdom and merit of virtue. Buddha did this, actualized the path, and achieved enlightenment, and then he revealed the Dharma, the whole path to enlightenment. He showed how to liberate sentient beings from suffering and its causes and how to achieve enlightenment, by removing even the subtle defilements from the mind. This is an example of how you should think.
If you can make charity of this money to the whole company, with a good heart, it becomes Dharma. It becomes virtue and charity, as practiced by bodhisattvas. Since you make charity with a bodhicitta motivation, you collect vast amounts of merit. What you actually achieve is amazing. Each dollar you offer brings the cause for enlightenment. This means you collect as many causes for enlightenment as the number of dollars offered. From this act of charity to sentient beings, you create so many causes for happiness in future lives and for the success of this life, and collect enormous merit.