How to troubleshoot clutch failure

When I was driving on the highway, I heard a couple loud knocks like something broke from near my engine.
Right after the sound, my car went out of gear and I had to pull over.

Now my clutch pedal has no pressure when you press on it, the pedal goes down and back unussually easy. It feels like theres no linkage.

Shifter will move into all gears, excluding reverse, but will not engage. Car can be pushed in all gears with clutch pedal depressed.

**clutch resivor still has fluid**

I been told many things, pressure plate, slave cylinder, clutch linkage, throwout bearing.

Any idea what needs to be replaced, or how to troubleshoot the problem? Needing to know how much parts and labor is going to be to fix this.

thank you!