How many years has it been since this problem arose?
Was it always like this or did it begin now, if yes, why do you think so?
Are you interested in your current line of studies? Are you unable to create and manage your study schedule or are they external factors affecting you or adding stress?
What are your results looking like... Average, good or below average?
Next Steps
Memory can be sharpened(read: The woman who changed her brain by Barbara Young).Create a steady daily routine with realistic goals. Look at some interesting methods that people use to study on Quora. Observe your overall lifestyle, health wise.
Health Tips
However, talking about your stress, concerns and issues in depth will also help. You may contact certain helplines that are there to listen or consult a counsellor you feel comfortable talking to.