Hi djr1718,
Here are a few things to look for, working on the principle that any internal combustion uses (ie. suck, squeeze, bang, blow,)it would be a good start to check the following:
Have you put in fresh fuel?
Is the carby getting fuel, and good fuel flow?
Has the engine got compression?
As Joe suggested, has it got a spark?
Is the plug new or the old one serviceable?
Is the muffler clear? (you would be surprised what can crawl in and make a nest!!)
Check these first, if it still won't run, we'll go futher
Best of luck,
