Sha, there are few things that are beyond our control. These are the times we realise how fragile we human beings are. Try this. Try remembering all the small things that you did from the time you woke up until you slept that day. For example, if today is Monday, before sleeping, try remembering all that ou did from the morning. Like which side of the bed did yu wake up, what you had for breakfast, which chair you sat, the minutest of the things. This will help you in being focused and keep you away from distractions. Slowly shift this to your subject. Try remembering sentence by sentence after reading a paragraph. This way all your focus and concentration will be centralised.