What is the solution for making up missed prayers, and how should a Muslim pray who finds it difficult to perform ablution and prayer during his work or studies that extend from Dhuhr until after Asr, or from after Asr until after Isha, or throughout the day, while he lives in a war zone and fears for himself?

We congratulate the questioner on her keenness to maintain prayer. Ablution is a condition for the validity of prayer, and if water is unavailable and there is a fear of the time expiring, then tayammum (dry ablution) is permissible. If you can perform each prayer at its designated time, that is what is obligatory. If that becomes difficult, then it is permissible to combine Dhuhr with Asr and Maghrib with Isha by delaying them, to alleviate hardship. However, if work occupies the entire day, then Dhuhr and Asr prayers must be performed together, as facilitated, and it is not permissible to delay prayer beyond its time under any circumstances, even if one is in a car. As for the prayers that were performed without ablution or without tayammum when ablution was impossible, they must be repeated.