Imagine that you (your consciousness) are divided into Child, Adult and Parent. These three argue every time on this or that issue. Now you are whining like a child. You need to include an adequate adult and understand what and why you are doing. Plus, learning something at home is harder than at school or university. Go to teach somewhere in the library, park, office. Change to a less relaxing environment.
The previous answer demonstrates a common "pull yourself together and overcome" position, which rarely works in practice. In fact, what you described speaks at least about stress and fatigue in your body, and a deterioration in mental performance can even be a symptom of depression. You should consider other features of your condition. Are there feelings of guilt, low mood, loss of energy, dullness of emotional reactions, problems with sleep? If the answer is yes, it is better to contact a psychotherapist or clinical psychologist (a psychologist is not a doctor, but can distinguish pathology from the norm and suggest what to do next). Please don't discount your problems and don't run them. They are much easier to deal with initially.
There are several options here. 1. Practice clearly and distinctly pronounce the phrase "Free cash!" 2. Read books or attend trainings on how to work as a seller in the market. 3. Stretch yourself and learn what you need to learn. And the last option is not the hardest thing that can occur in life;)