Well i wish it was that easy.
It depends on y u are trying to forget. if u have had arelationship with this gu there must have been hard times. however bad it sounds u must try and focus on these. People make the mistake of when someone leaves them just focusing on the good times and it makes them miss them more.
You need to see your friends as much as possible, go out and have fun.
If you do not have many friends, get some. start a new hobby, a new sport. it doesnt matter if u feel u are not good at a sport, that's what clubs are for to teach u to get good.
You need to look after yourself, be happy with yourself, have bubble baths and make yourself look nice.
you will meet someone else when the time is right.
About 2 years ago i had to do the same as you and it was terrible, so hard to forget but i focused on the above things and i am happiliy married to some other guy now and the one before is just a distant memory.
You need to be strong and the most important thing is to keep loving yourself.
good luck.