I apologize in advance for the long answer, but I wanted to give you the full picture.
There are 3 parts to the answer: 1. Do you really need a co-founder? 2. Why haven’t you been able to find one, and 3. How to find a co-founder.
Do you really need a co-founder?
A) You should be 100% sure that you really need a co-founder (versus using a freelancer or employee which may be sufficient).
B) Investors usually take a deep look into the team and prefer founders that have worked together for some time and/or know each other for a minimum period.
C) Based on research done by CBInsights, the 3rd most common reason for startup failure is: “not the right team”. The most common agreement that I draft as a startup lawyer/mentor is a ‘separation agreement’. The reason being that most co-founders eventually split – and usually not as friends.
In most cases, freelancers/employees can do what you need (the only exception is having a CTO when trying to raise capital from VC’s - and even this depends on the type of startup).
Analyzing the problem - why haven't you been able to find a co-founder?
a) Is it because the idea isn't 'good' enough? That you're not presenting it well? Or maybe that you're not pitching to the right people? If it's a pitching problem, I can help you improve your pitch. If it's the wrong people, you can network in other areas/groups. If it's the idea, I’m happy to try help you refine it.
If you can't recruit a co-founder, you may have similar difficulties raising capital from investors - the reason being that pitching to a potential co-founder is very similar to pitching to investors. Co-founders invest time, efforts & money. Investors invest money. Both take a risk and therefore have to fall in love with the idea or the potential for profits.
How to find a co-founder:
1. Go to networking events - some of which are dedicated to “co-founders dating/matching” - try www.meetup.com for this. You can also try www.founderdating.com or www.cofounderslab.com or http://www.founders-nation.com or www.founder2be.com
2. Take part in chats in relevant forums (depending on the type of co-founder you’re looking for).
3. Consider joining accelerator/incubator programs for startups/entrepreneurs - some of them connect between founders.
4. Contact head of programs at universities and tell them what you’re looking for. Today, many universities and cities have startup programs with a lot of talented participants (or speakers) who might be the perfect co-founder for you.
5. Talk to friends and family and let them know that you’re looking. This helps expand your network. Post a message on www.LinkedIn.com .
I've successfully helped over 300 entrepreneurs. I'd be happy to help you. Good luck