Talk to your family, friends or teachers. Maybe they will be able to get you out of here and inspire you to start again.

You should not be afraid of starting again, because the next time you start again you will be stronger.

Stop thinking negative about yourself, rather try to improve. There is no use of negative thinking other than just to waste time.

Lack of motivation or inconsistency is common in our lives, because we are not robots. The thing is to get back up quickly and stronger!

Whenever you feel like giving up, always remind yourself of the reason why you started and what could be the outcomes. 

You have not reached this far just to reach this far.

...even if you don't feel like, because if you start now, at least you will not waste your present time and regret about it later. 

Identify where you are going wrong, and what exactly is causing the lack of demotivation.

Make a fresh plan keeping in consideration those problems.

There is nothing constructive in regretting, it will just waste your time. Once you have identified where you went wrong, stop the guilt and get back on track quickly!

Who doesn't know practicing meditation regularly can help calm down the brain and improve focus, etc. So if you feel really distressed, you could try out meditation.

Last but not the least, it's okay! Move on, because change is the only constant. 

Start again, and make sure from the next time you are prepared before hand for such situations.