I have a yard machine 6.75 hp. I tried to start it and the pull string will not move out. I didn't want to try to force it out afraid to break it. What can I do to fix this please

If it is in gear it won't move. Some have gears some don't. It has to be in neutral. If it is in neutral, make sure it has plenty of gas. You can also prime the carb with a small amount of gas. Make sure it is well oiled. Other than that it may have to be taken apart.

Yard machine what, mower, tiller, etc... Remove the spark plug and tell us if this makes any difference.

OK that problem is fixed,but now when I try to start it it smokes very bad and then oil comes out of muffler.What would cause this

Oil over filled. Mower on the side for a while.

First, do this:

Take out the plug.
Put carb cleaner in the spark plug hole.
Put a rag over top the hole.
Crank until you get the muck out.

Re-install plug.

Check the oil level.

Check to make sure the air cleaner is free of oil as well.

Carb cleaner makes excellent starting fluid. Don't use starting fluid in a small engine. Use carb cleaner as starting fluid.