When motivation to learn is lost, you first need to understand what caused it. Perhaps, worsened relations with schoolmates or classmates. In this case, is to try to establish, or to stop paying attention to it. If there are no other options, you can switch to another class.
Another reason for loss of motivation may be weak faith in their capabilities. When you lose faith in yourself, there is a fear of failure. And for many, access becomes not just take on any case, because then there will be no failures. Increasing the motivation in this case depends directly on the increasing faith in yourself. It is important to keep trying to learn no matter what, only then success is possible.
Motivation may decrease when the learning rate does not match the expected pace. To resolve this problem, it is necessary to understand the reasons and think about your own growth.
Another option loss of motivation is lack of interest in learning. In this case, it is necessary to diversify the training. Perhaps it is the viewing of interesting films and videos related to the studied subject, or turning the learning process into play, most importantly to represent the school in a different, more interesting light.
Perhaps the motivation faded due to the lack of fun in the learning process. This happens when more likely to notice your failures, rather than successes. In this situation it is important to switch the attention to small successes and rejoice in any intermediate results.