Outdoor Power Equipment and Small Engines - Need help.I can't pull the string on my Ryobi trimmer.

My 2 years old 30cc Ryobi string trimmer worked well before it lost power.I replaced the new spark plug and worked with it twice then no longer I could pull the string.I don't know why?Please help since I'm a newbie with this kind of the problem.
Thanks in advance.

Find your model here http://www.ryobioutdoor.com/manual.jsp
Most likely the pull rope is just wrapped wrong around the rewind spool. If you remove the 4 bolts that holds the rewinds assy cover and shaft you should be able to pull it back far enuff to see the rope and spool. Usually the rope will just get looped and not rewound correctly. I have noticed this is usually caused by the rope being fed back into the rewind assy faster than the spring loaded spool can take it up.
3 pulls should get at least one fire from the unit or further troubleshooting is required.

Thanks for responding and helping. I did took out the rope and spool,I pull with ease and it rewind properly.I cleaned the carb too.The rotor has 2 gear that attached to the spool would not rotate when I try to turn.I think that is why I could not pull the rope.
You have any idea on how to fix it,please help.
My trimmers model is BC 30 RY30061A and not on the manuals list.The manuals I got when I bough this one does not help with any of the problems.
There is not any repair shop within 30 miles of where I live.
Thanks in advance.
________
tranxyz

Sounds to me like the engine is locked up. Was it run without oil in the gas? If so, it's not worth repairing.