Disassemble as seen in this parts List attached below and examine for stripped or broken parts.

Good Luck!

http://www.ereplacementparts.com/ryobi-ry30020b-string-trimmer-parts-c-7931_15633_15661.html

Here is a link that might be useful: Parts List

Drive shaft cable twisting up getting ready to fail or broken strands is my guess. If it's split boom you have two. Usually the upper cable fails first especially if you run attachments like edger, blower, or culivator which put alot of torque or twist on the cable shaft.. Can only get the upper shaft assy. was 30 bucks last time I brought one?

The start/choke lever is also broken off. I can move the lever shaft via a finger. It's the little round orange shaft with the spring on it. I get it started eventially - but I would really like to know if the lever shaft is supposed to move the upward position or down. It seemed that the nut on the endof the spool shaft was loose. So removed the trimmer section off the main shaft - put a little vise grip on the upper cable that connects to the main shaft - to keep it from spinning - and tightened the nut on the end of the spool shaft. Cranked up the trimmer and seemed to solve the problem. I don't know if that's an appropriate solution - but I got the trimmer for free - what's to lose.

Take the air filter off and see when you move wheather it choke is closed or open. Then mark it to the choke side, usually (not knowning model) there's a stamped picture of the choke showing closed and open on the side of the air filter housing???