2000 350 Manual Trans Problem

[sailj22]

No mods with a 410 rear. Stick won't go into 1st or 2nd while idling or running. Double clutch does not do any good either. R-L-3-4-O are fine and go without issue. This suddenly happened while driving and shifting from 1st to 2nd.

Any ideas?

What is worst case scenario cost wise for clutch/rebuilt tranny/ everything else replaced while at it? I will not be doing it myself.