Chainsaw will not start?

Hi,
I got this chainsaw of my mate and it will not start. He told me that it was the ignition switch so i took it off and it still dosent work. Cause usally lawnmower engines, petrol trimmers and all that can start without a switch. The chainsaw dosent have the best compression. I have inserted an new sprak plug and new fuel but still dosent want to go. All answers are very welcome thanks.