How to move on if my crush rejected me?
I can't stop looking for him. Help. Plus, I still have assignments to do.
I'm very sorry about that. :(
When I went through a rejection, I found distractions helped me. Reading, writing, hanging out with friends who have no connection to the crush, etc. were some of the things I did. Also if you have him on your social media it would be best to either block or unfriend him , or at least hide his posts so you won't be tempted to hope for something more.
Is this crush still your friend or were you just acquaintances? 'cause that changes the dynamics. If he's a friend then you could tell him that you need some time for yourself after what happened (and make the best of that time, find distractions, hang out with friends, etc). If you guys weren't that close to begin with then walking away completely would be the best thing to do.
Rejection is tough. But the most important thing to remember (in my experience at least) is that everyone needs their own time to get over it. Find your own pace and don't rush things.
Best of luck 
I'm going through the same sort of thing at the moment, so I know how tough it is.
Removing them from social media was mentioned, and if there is no other reason you might need to contact them that's something you should definitely do. It also might be helpful to completely take a break from social media for a while, since you are likely to see posts from other friends that will make you think about them. In fact it's kind of helpful in general since we tend to compare ourselves to others, but on social media you only see the highlights of other peoples lives, and so you can start to feel inferior in comparison.
The other thing is, wherever possible avoid doing things/going to places where you know you are going to see them. There may be things it's not appropriate to avoid (eg if you have classes with them or something). Also try and keep yourself occupied, particularly with rewarding activities such as getting your assignements done, and spending time with friends. Also, try not to get annoyed or angry at yourself for thinking about them, accept the way things are and acknowledge that you need to move on but also recognize that it will take time. I personally found just taking a break from Facebook and stuff for a few weeks made me feel a lot better, so I think its worth considering, so long as you would still able to contact your friends, as you really need their support.