What is the ruling regarding the Dhuhr, Asr, Maghrib, and Isha prayers for the day on which I was unable to perform ghusl from janabah due to illness? And is wudu and prayer sufficient, or must the prayers be delayed until ghusl is performed?

If you are unable to perform a full ritual bath (ghusl) due to illness but are able to perform ablution (wudu) or wash part of your body, then you should wash what you can and perform tayammum (dry ablution) for the rest. You are also obliged to make up the prayers that you missed before performing the ghusl, knowing that negligence in learning one's individual obligations (fard al-ayn) is a grave error.