ignition switch removal

the tumblers fell in my switch and now the key will not go in and I can't turn it. How do I replace the switch now?

Welcome rlrufus

You will need to "pop" the cylinder, insert a large flat screwdriver as far as you can, or use a flat screwdriver socket and a 3/8 wrench and give it a turn towards the run position which is where you should stop and then insert a small drill bit into the hole under the column to push the retainer pin in the cylinder.
Once you break the cylinder to the run position and push in on the pin, the cylinder will come out.
Should be about 10-20 bucks at an autowrecker with key.

your refering to the lock cylinder not the switch so be sure to ask for the right part also without a key forcing the mechanism into the run position may damage the column be careful when doing this you may wish to seek a locksmith