I wanted to ask when I am on my menstrual cycle, I cannot pray or read. What can I do or recite to keep my imaan strong.

At the time of prayer, you can do wudhu and sit on the prayer mat and recite duas such as Ziyarat e Ashura, Dua e tawassul, salawat or any other dua/tasbeeh you wish to recite. You can also recite the Qur'an excluding verses which contain wajib Sajda.