I always found this to be the must frustrating "problem" with fundraising. It doesn't matter if you are excellent at all the other parts, if you have no names to call you feel like you are just spinning your wheels.
I like Jack's suggestion, obviously taking the time to quiet yourself and pray through it is a great strategy because ultimately we are dependent on the Lord's provision in all things and spending time in prayer is always better than sitting around feeling frustrated
You might also try a tool to help jog your memory, for some people it's looking through their facebook friends (and friends of friends), your email contacts, your parent's address book etc.
I created a free tool to help people with name storming - there's a link on the supportgoal home page if you want to try it out: https://www.supportgoal.com/namestorm