Hmm, I don't really know something like 'tháts it!', but it's probably something like this; your clutch is disengaged all the time, just like when you push in the pedal.
Maybe something got stuck when you put into first after reversing.
Where? dunno, but here are a few theories about what it MIGHT be;
- clutch pedal sticks,
- clutch master or slave cylinder sticks,
- clogged up or blocked clutch lines (unlikely tho),
- broken release bearing (does something rattle?),
- burned flywheel causing the clutch to burn (forming a glass-like surface, like brake pads do when they overheat) so it slips ALL the time (does/did it smell?).
Look into these things, and get back at us with the answer
