How does one rely upon Allah Almighty when all means are cut off and there is a seemingly insoluble worry, and how can a person not despair under these circumstances?

The believer does not despair of Allah's mercy, for everything is by divine decree and destiny, and Allah decrees nothing but good for the believer. If good fortune befalls him, he is grateful, and that is good for him. If adversity befalls him, he is patient, and that is good for him. The believer submits his affair to Allah and relies upon Him, while taking lawful means. "And whoever relies upon Allah, then He is sufficient for him." (Quran 65:3). Knowing Allah's beautiful names and attributes, such as Al-Aziz (The All-Mighty), Al-Rahim (The Most Merciful), Al-Sami' (The All-Hearing), and Al-Alim (The All-Knowing), increases reliance, for Allah sees His servant and knows all his states. Reflecting upon the Book of Allah, seeking help through patience, prayer, and supplication, and maintaining remembrance of Allah (dhikr), all help to relieve worries, for after every hardship comes ease.