Opel Corsa 1.7 DTI?

I have a problem, it happen recently, i was driving to my nearest town then when i was in middle of the trip about 30 km, my car started to loose contact with the wheel. then i parked at the side of the road. Suprisingly the gear was still enganged. then i swith off the engine attempting to get help from someone to tow me . luckily he arrived the we towed the car home, on arrival i started the car again and engage the gears again it they started to engage with wheels, after a while while i was driving again around similar proplems started. what is the main course of this? And how can it be fixed