AC clutch front plate fell off

ac stopped working after my wife heard a noise, 99 CRV with 162K miles,found the front plate and a nut on the plastic underneath. weird thing is the end of the shaft doesn't appear to have broken off but it's now flush with the rest of the clutch innards and doesn't stick out enough to replace the piece. it really looks like a finished end, not a stub but the only way that could be is if the shaft slid inside after the plate nut fell off- not possible, i would guess, so i'm baffled. could be the compressor is seized up but i can't turn the shaft until i can get the rest of the clutch out of the way and haven't had the time just yet. anybody had dealing with their ac like this?