Marks & Spencer experienced a sustained cyber-attack over Easter weekend, resulting in significant financial losses and operational disruptions.The retailer has halted online orders, faces stock management challenges, and is unable to provide full service to customers.The chief executive has called for in-store shopping as online system restoration may take weeks to months.Despite initial disruptions, M&S has resumed certain services such as contactless payments and gift card acceptance.The cyber-attack has impacted food deliveries to Ocado and led to food waste due to IT-related pricing issues.The retailer's flagship store showed stock shortages in both groceries and clothing, prompting in-store visits.Analysts estimate a substantial profit loss for M&S, with ongoing impact expected to reach £15m weekly.Although customer data security remains intact, the cyber-attack has significantly impacted operations and profits.M&S is working to restore systems, but the ransomware incident has already affected its annual profits and market value decline.The National Cyber Security Centre is involved in the investigation, emphasizing the need for robust cybersecurity measures in the retail sector.Rival retailers are on high alert following cyber-attacks on M&S, Co-op, and Harrods, prompting a reevaluation of their security protocols.