For example, tell me:
* What type of engine is it? (Gas, diesel, electric?)
* What is it powering? (Mower, chainsaw, generator, etc.)
* What have you already tried to start it? (Pull cord, electric start, etc.)
* What are the symptoms? (No sound, backfires, runs briefly, etc.)
The more information you provide, the better I can help you troubleshoot the issue.