Short-term memory loss can be caused by vitamin deficiencies such as B12, stress, depression, thyroid problems, lack of sleep, certain medications, or other underlying conditions. To improve memory, try to get adequate sleep, eat a balanced diet, exercise regularly, manage stress, and engage in regular mental stimulation with activities such as puzzles or reading. If the problem persists or worsens, please consult a doctor to find out the exact cause and receive appropriate treatment.