Car won't move after clutch disc replacement (My Summer Car)

It's time to replace the clutch disc. I took off the old disk, bought a new one from the mechanic, installed it, assembled everything and twisted it in the same way as I disassembled it - the gears are switched, but the car does not go. I rechecked all the bolts 1000 times, reassembled everything several times, everything is there. I don't know what else to do, please help.