Welcome to the forum. You've found the right place for help with your motorized bicycle.
We do ask that when seeking advice or answers to your questions that you tell us what engine you have. Troubleshooting gets much easier if we know what we're looking at.
From your manual clutch reference we'll assume you have a Chinese 2 stroke engine. We have a troubleshooting section and it is headed by a very good tutorial that will give you a starting point on what to look for if the engine doesn't run. Here's a link to that thread > http://motorbicycling.com/showthread.php?t=35090
Good luck and let us know what you find.