My very best advice is to get out with your mates and do some of the things you like doing (even if you feel like nothing is worth it at the mo). It takes a while but eventually you start to enjoy being single and that when another relationship comes out the blue.
You may feel like you have to go on the pull to prove yourself but don't bother, birds can smell desperation a mile away and you'll feel even worse for getting knock backs. It's when you stop looking and go out for a night out with the lads and a lagh that girls see confidence in you and want to know.
Good look pal, remember the good times forget the bad times and never look back. It ended for a reason and that never changes.