What is the ruling of Islamic law regarding my continuation of a project that began with money taken from the company's trust fund without my manager's knowledge? Am I obligated to return profits from this money to the trust fund? And what should I do to make my earnings lawful after repenting from this action?

Taking money from a trust without permission is forbidden and a betrayal of the trust (amanah). One must seek forgiveness from Allah and repent for it. Any profits generated from this money are to be divided into two halves: half for you in return for your effort, and half to be returned along with the original amount taken. If it is impossible to return it, then it should be given as charity to the poor and needy.