How can an employee who does not understand business invest his saved money to avoid the decline in its purchasing power, while staying away from usury and the suspicions surrounding banks, and without risking his small savings?

It is not permissible to deposit money in interest-based banks except in cases of extreme necessity, such as fear of theft. The loss of the money's purchasing power is not considered a justification for this. Money can be invested through legitimate mudarabah (profit-sharing) with a trustworthy person, or by depositing it in Islamic banks. One should not rely on satellite channels for knowledge of Sharia rulings unless the mufti is among the trustworthy people of knowledge.