Is the salary and money earned from working in an investment bank permissible or forbidden, and what should I do if I cannot find another job and I have a family, and is it permissible to start a private project with this money?

It is not permissible to work in an interest-based bank, due to the assistance in sin and participation in writing and recording usury that it entails. The Prophet, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses, and he said: "They are all equal." The money obtained from this work is unlawful and must be disposed of by giving it to the poor and needy, along with leaving the job and searching for another. We hope that Allah will forgive what was consumed and spent from this money. And whoever gives up something for the sake of Allah, Allah will compensate him with something better.